The 7th international conference on particle physics and astrophysics

The BM@N (Baryonic Matter at Nuclotron) is the first fixed-target experiment performed at the NICA-Nuclotron accelerator complex. In central heavy nucleus-nucleus collisions at the Nuclotron beam energies, baryon densities of 4-5 of the saturation density are reached. The primary goal of the experiment is to constrain parameters of the equation of state of high-density nuclear matter and search for the onset of the deconfinement phase transition. The main aspects of the physics program of the experiment and the relevant observables are discussed.
Previously, the experiment recorded the first data in carbon-nucleus and argon-nucleus interactions at beam kinetic energies from 3.2 to 4.5 GeV per nucleon. In 2023 the physics run was performed with a xenon beam of 3.8 A GeV and 3.0 AGeV. The experiment recorded over 550 million Xe+CsI interactions in a full set of detectors. The experiment is currently on its way to studying relativistic interactions of heavy nuclei up to Bi+Bi.
First physics results of the experiment are presented on the yields of charged pi+, K+, proton, deuteron and triton yields and their ratios in argon-nucleus interactions at a beam kinetic energy of 3.2 AGeV. Preliminary results on the production of Lambda, K0s and the measurement of direct collective flow of protons in Xe+CsI interactions are also discussed.

The main heavy-ion experiment at Nuclotron-based Ion Collider fAcility (NICA) is the Multi-Purpose Detector (MPD). It covers the energy range from 2.4 to 3.5 GeV in fixed-target mode and from 4 to 11 GeV in collider mode. This allows us to examine the region of the QCD phase diagram with a high baryon chemical potential, where a first-order phase transition and the onset of the critical endpoint are predicted to occur. Preparations for data collection in the MPD experiment will be concluded in 2026. The study of hadron spectra and hypernucleus production, collective flow, correlations and fluctuations, hyperon global polarization, electromagnetic probes, and open charm production are important contributions to the MPD physics program. In this talk, the project’s current status and recent results of the feasibility study will be presented.

SPASCHARM experiment at U70 accelerator complex at NRC "Kurchatov Institute" has obtained first physics results. Overview of the experimental program including first results and complete program of spin studies are presented.

The talk is devoted to the latest results from the OKA collaboration. The OKA setup is using the RF-separated 17.7 GeV/c momentum kaon beam of the U-70 accelerator. The data corresponds to the flux of $2.62·10^{10}$ «live» kaons entering the decay volume.
A missing mass analysis is performed to search for an invisible pseudoscalar axion-like particle(ALP) in the decay $K^+ \rightarrow \pi^+\pi^0 a $. No signal is observed,the 90% CL upper limit is changing from $2.5·10^{-6}$ to $2·10^{-7}$ for the ALP mass from 0 to 200 MeV.
Several rare EM decays are investigated:
A new precise measurement of the vector and axial-vector form factor difference $F_V − F_A$ in the $K^+ \rightarrow \mu^+ \nu \gamma$ decay is reported. About 144K events are selected. The preliminary result is $F_V − F_A = 0.135 \pm 0.017(stat)\pm 0.024(syst)$ which differs by $\sim 3 \sigma$ from $χPT(O(p^4))$ and by 1.5 σ from the Lattice calculations.
The $K^+ \rightarrow \mu^+ \nu \pi^0 \gamma (K\mu3\gamma)$ decay is studied with the high statistics of more than 1000 signal events with the energy of the emitted photon in the rest frame of the decaying kaon $E_\gamma > 30$ MeV. Using $4.48 · 10^6$ events of the decay the ratio Br($K\mu3\gamma$)/Br($K\mu3$) is found to be $(4.45 \pm 0.25(stat)) · 10^{−4}$. From this value, using Br(Kµ3) = 3.352% we get Br($K\mu3\gamma) = (1.492 ± 0.085(stat)) · 10^{−5}$. Our result is preliminary, with systematic errors being estimated.
A rare EM decay $K^+ \rightarrow \pi^+ \pi^0 \pi^0 \gamma$ is observed for the first time on the statistics of ~50 events with $E_\gamma >10$ MeV. The branching is measured to be Br$ = (3.7 \pm 0.9 \pm 0.3 ) · 10^{-6} E_\gamma > 10$ МэВ
A super-rare EM decay $K^+ \rightarrow e^+ \nu \pi^0 \pi^0 \pi^0 $ is searched for, no events were observed, the upper limit set is: Br$ < 5· 10^{-8}$ , ~60 times better than in the previous searches.

Search and study of exotic hadrons - tetraquarks and pentaquarks - is one of topical problems in modern high energy physics. To determine spin-parity of these states, test theoretical predictions of their spectra and reveal the internal structure - high-precision measurements of their parameters are required. Amplitude analysis is a recognized tool for solving this problem. In this report, the details of amplitude analysis approaches together with practical examples of their application will be presented.

The purpose of the present work is calculation of the cosmological perturbation spectrum in a flat model with a scalar field in the slow-roll regime. Mukhanov’s gauge-invariant approach for calculating the spectrum of gravitational perturbations is analyzed. In contrast to Mukhanov’s paper [1] we calculate perturbation spectrums of gravitational and scalar fields separately. We use action of the system in the invariant form, quadratic for perturbations. Obtained expression leads to the equations for gravitational and scalar perturbations, by using slow-roll approximation. To calculate the perturbation spectrum, we need to solve these equations. As shown the solutions are ambiguous and depends on chosen approximations, so we are not able to obtain clear-cut solutions. So, it is desirable to look for other approaches to solve the discussing problem.

[1] Mukhanov V. F., Feldman H. A., Brandenberger R. H. Theory of cosmological perturbations. // Phys. Rep. 1992. Vol. 215. P. 203 – 233

Cosmic rays with energies above $10^{19}$eV, observed in 1999 - 2004 by the High Resolution Fly's Eye (HiRes) experiment in the stereoscopic mode [1], were found to correlate with directions to distant BL Lac type objects (BL Lacs, which constitute a subclass of blazars, are active galactic nuclei with jets pointing to the observer), suggesting non-standard neutral particles travelling for cosmological distances without attenuation. This effect could not be tested by newer experiments because of their inferior angular resolution. The distribution in the sky of BL Lacs associated with cosmic rays was found to deviate from isotropy, which might give a clue to the interpretation of the observed anomaly. However, previous studies made use of a sample of BL Lacs which was anisotropic by itself, thus complicating these interpretations. In this work authors use a recently compiled isotropic complete sample of BL Lacs and the same HiRes data to confirm the presence of correlations and to strengthen the case for the local large-scale structure pattern in the distribution of the correlated events in the sky.

The paper presents a clarified database of the parameters of beta-active nuclei, which includes previously unknown and inaccurately estimated parameters. The parameters were obtained by using our developed method of converged sequence of calculated energy spectra to the resulting spectrum, which is most close to the experimental one. Rovno experimental spectrum was taken as the experimental one. Beta-active nuclei parameters used for calculating the resulting spectrum were included in clarified database. The use of this data base allows to get the best coincidence of calculated antineutrino spectrum with the measured one at any nuclear reactor core content.

In this paper, we propose a method that makes it possible to use an ultrathin calorimeter for direct measurements of cosmic rays with energies of TeV and higher. The problems of determining the primary energy with a thin calorimeter, due to large fluctuations in shower development, the low statistics of analyzed events and the large size required for the calorimeter, are considered in detail. A solution to these problems is proposed on the basis of a lessening fluctuation method. This method is based on the assumption of the universality of the development of cascades initiated by particles of the same energy and mass. For energy reconstruction, so‐called correlation curves are used. The main analyzed quantities are the size of the cascade and the rate of its development. The method was tested using a heterogeneous calorimeter consisting of 22 layers of tungsten absorber and silicon detector. Based on simulations, it is shown that the primary energy can be determined on the ascending branch of the cascade curve. This fact solves the problems associated with the need to increase the calorimeter thickness with an increase in primary energy and with the limitation of the analyzed events. The proposed technique is universal for different energies and different nuclei.
The study was carried out with the financial support of the Ministry of Education and Science of the Republic of Kazakhstan (grant No. AP22785312).

The NOvA experiment aims to study neutrino oscillation parameters using an accelerator complex. Far detector big size and high segmentation structure as well as a flexible system of software triggers and data acquisition allows to detect the atmospheric neutrinos and study their parameters in NOvA.

This work presents the developed technique of atmospheric neutrinos registration in the far detector: the selection and reconstruction of triggers, the calculation of their efficiency for background and signal events, and finally the expected energy spectrum of atmospheric neutrinos.

In this paper, a set of programs is presented that allow obtaining angular distributions. For testing, the reaction 10В(7Li, 6Li)11В was used at an incident beam energy of 58 MeV. The experiment was done using the U-400 accelerator beam of the FLNR JINR, Dubna. One of the goals of the experiment was to study the excited states of the 11B nucleus. The obtained differential cross sections are planned to be described using the Distorted Wave Born Approximation method (DWBA).

The MPD detector at the NICA facility is under construction. One of the key subsystems of the MPD experiment is the electromagnetic calorimeter ECal. The ECal modules are calibrated using cosmic muons. Signal from SiPM of each tower is digitized by the ADC in a 640 ns window. The purpose of the calibration procedure is to establish a correct relation between the measured signal and real energy deposition of the muon in the tower material. But there are many processes that can deteriorate this correlation. Among them are random cosmic particles, large noise pulses, crosstalk in SiPM cells, etc. In this contribution, we present a simple and fast method for suppressing such background. It is based on the analysis of the ratio of the signal integral to the maximal amplitude. For good events, a good parametrization of the dependence of the ratio on the signal amplitude was found. The compatibility of the parametrizations evaluated for 768 towers of one half-sector is discussed. Selection criteria for background rejection and their efficiecny as well as contribution of the crosstalk to the backgrouns are presented and analyzed. The contribution of the crosstalk to the background was estimated.

The results of a study of detectors made of silicon carbide (SiC) and silicon (Si) are presented. The irradiation was carried out using exemplary spectrometric α-sources with energies $E = 4.8 - 7.7$ MeV. The thickness of the epitaxial layer of the n-type SiC detectors was 25 and 50 microns, with a contact diameter of 3.0 mm. The initial energy resolution of the detectors was <25 keV. Si detectors were manufactured using planar technology on n-type silicon, with a working area of 7 mm$^2$ and a thickness of 300 microns.
The radiation resistance of SiC and Si detectors was studied before and after irradiation with alpha particles with integral fluxes up to about $1.6\times10^{11}$ $\alpha/cm^2$.
It is shown that degradation was observed after irradiation with α-particles: peaks from α-particles shifted towards smaller channels and became wider. It was found that with an increase in the radiation dose, the energy resolution deteriorates up to 11.5 times for SiC 50 microns, up to 3.5 times for SiC 25 microns and up to 2 times for Si. At the same time, the charge collection efficiency η (CCE) decreased from 100% to 85% (operating voltage 300 V) for SiC 50 microns, from 100% to 95% (operating voltage 200 V) for SiC 25 microns and from 100% to 98% (operating voltage 100 V) for Si at the maximum radiation dose.

The study of the momentum spectra of charged particles allows one to obtain information about the thermodynamic characteristics of system arising from the collision of heavy ions. This research can improve the understanding of their interactions and dynamics in various physical processes.

The aim of this work is to study the momentum spectra of pions, kaons, and protons in Ar+Ar and p+p at energy $\sqrt{s_{NN}} = 11$ and 27 GeV, respectively, by using the UrQMD (Ultrarelativistic Quantum Molecular Dynamics) model for the SPD experiment at NICA. The spectra are presented as a function of transverse momentum and collision centrality. The extracted kinetic temperature for the protons, pions and kaons was obtained using hydrodynamic Blast-Wave approach based on Boltzmann statistics. Physics implications will be discussed.

The centrality determination procedure provides an estimate of the initial geometry in heavy ion collisions through a connection between the observable and the impact parameter. The multiplicity of produced charged particles and the two-parameter Glauber model is usually used to determine the centrality. However, there are difficulties in using this approach at NICA collider energies due to the large uncertainty of the impact parameter at small multiplicity, autocorrelation effect, etc.
New approach to determine the centrality based on Bayes' theorem and two-dimensional Gamma distribution is proposed. This method allows to obtain information about the impact parameter by using only the measured two-dimensional energy distribution of spectator nucleons and the multiplicity of produced charged particles. A new method to account for the efficiency of the detector system and the pileup is also proposed. The performance of the proposed approach has been tested on simulation data from the DCM-QGSM-SMM model for Xe+CsI collisions at a beam energy of 3.8A GeV. The GEANT4 software package was used for a realistic response of the BM@N detector system.

We consider axion-like particle (ALP) model to construct numerical spatially homogeneous anisotropic Kantowski-Sachs cosmological model. We present our first-step approximation on analysis of the background' dynamics of domain wall, induced by ALP scalar field. We consider limiting case far from the wall itself, yet we found non-trivial behaviour of the space-time.

Inflationary expansion is one of the most promising models allowing one to describe the properties of the early Universe and its later development. In the simplest realisation of the inflationary scenario, it is generally assumed that after the Universe leaves the inflationary stage and post-inflationary reheating, it remains at minimum potential with a value of $\Lambda \sim 10^{-47}$ GeV$^{4}$ or $10^{-120}$ in Planck units.

In this work, we show that quantum corrections to some cosmological models [1,2] can lead to a significant modification of the behaviour of the initial potential and the appearance of a non-zero ground state energy of the Universe which can be interpreted as a cosmological constant.

We apply the formalism of the effective potential to the simplest forms of $\alpha$-attractors which can be represented by the so-called $T$-models and $E$-models [3]. However, simpler models, say, such as arbitrary degree potentials, we have considered in [1].

We derived the generalised renormalisation group (RG) equations that sum up the whole sequence of leading logarithmic contributions to the effective potential. As a result, the accounting of quantum corrections leads to a change of character and a lift of the effective potential [4,5]. We interpreted this uplift as the appearance of the cosmological constant $\Lambda$ for the $T^{2}$ and $E^{2}$ models.

Thus, we have found out that the cosmological constant $\Lambda$ may exist as a consequence of quantum corrections to the effective potential with some value of the scale transmutation parameter $\mu$ even in non-renormalizable models of inflation. And the value of the cosmological constant $\Lambda$ allows one to fix the parameter $\mu$ which is a free parameter in the non-renormalizable theory.

[1] D. I. Kazakov, R. M. Iakhibbaev, and D. M. Tolkachev. Leading all-loop quantum contribution to the effective potential in general scalar field theory. JHEP, 04:128,2023.

[2] D. I. Kazakov, R. M. Iakhibbaev, and D. M. Tolkachev. Leading all-loop quantum contribution to the effective potential in the inflationary cosmology. JCAP, 09:049,2023.

[3] Renata Kallosh, Andrei Linde, and Diederik Roest. Superconformal Inflationary $\alpha$ -Attractors. JHEP, 11:198, 2013.

[4] Tolkachev D. M., Kazakov D. I., Iakhibbaev R. M., and Filippov V. A. Quantum corrections to effective potentials of simplest 𝛼-attractors. PoS, ICPPCRubakov2023:022,2024.

[5] D. I. Kazakov, R. M. Iakhibbaev, D. M. Tolkachev, and V. A. Filippov. Dark energy due to quantum corrections to effective potential. In preparation.

Consideration of $\left(\alpha,n\right)$ reactions is necessary for conducting precision experiments on detection and study of neutrinos and dark matter particles in modern ultra-low background installations. As a result, computational tools such as NeuCBOT are emerging that facilitate the evaluation of the background caused by $\left(\alpha,n\right)$ reactions. The NeuCBOT utility originally uses the TENDL database, obtained with the TALYS software package, to calculate the neutron yield and spectrum. However, using this approach, the output data seems to be overestimated and the spectra are likely to be distorted.

The NeuCBOT utility has been upgraded by adding an ability to use new input data obtained from the JENDL database. Its advantage is that it contains evaluated experimental data. As a result an universal algorithm for calculating the kinematics of $\left(\alpha,n\right)$ reactions and data processing for subsequent use in calculations within the NeuCBOT utility were created. Neutron yields and neutron spectra for $\left(\alpha,n\right)$ reactions based on JENDL data can be obtained now, including cases for individual channels of $\left(\alpha,n\right)$ reactions when the final nucleus is in an excited or ground state. This new option is available for the following target nuclei: $^{6-7}$Li, $^{9}$Be, $^{10-11}$B, $^{12-13}$C, $^{14-15}$N, $^{17-18}$O, $^{19}$F, $^{23}$Na.

The Electron String Ion Source (ESIS) is type of electron beam ion source working in a reflex mode under specific conditions. The operation is based on step-by-step ionization of the ions by hitting with electrons of an electron string. ESIS is a complex facility and ion trap control system is its important part. It affects ion beam formation process and transfer to NICA HILAC. The version, which is under operation now is based on resistance divider. The new system is based on independent modules and could make operation process more flexible. The paper describes development of the ESIS ion trap control system electronics, its modifications and operation process.

Background radiation estimation is an important part of the process of planning and conducting experiments in high energy physics. The aim of this work is not only to calculate radiation doses for the safe conduct of the new short-range correlations experiment using Geant4, but also to compare with the results obtained using FLUKA.

The Tokai-to-Kamioka (T2K) [1] is a flagship long-baseline accelerator experiment located in Japan. T2K is designed to measure neutrino oscillation parameters and further probe CP violation in the lepton sector of the Standard Model. The near detector ND280 [1] is an essential part of the experimental facility. The detector studies various interaction channels, the flavor content and energy spectrum of the un-oscillated neutrino beam. Its data are used to tune parameters of the cross-section and flux models, thereby reducing systematic uncertainties and enhancing the precision of neutrino oscillation measurements. ND280 is a complex apparatus consisting of several modules. The structure leads to various sources of systematic uncertainties related to simulation and tracking of neutrino interaction products. The methods used to estimate the systematic errors and to propagate them through the stages of the oscillation analysis will be presented in the poster.

[1] Abe K. et al. [T2K Collaboration], "The T2K experiment", Nuclear Instruments and Methods in Physics Research, vol. 659, 2011.

Observations of extensive air-showers is characterized by the combination of a relatively narrow field of view of the telescope with an even narrower angle of propagation of Cherenkov light from the shower.
With increasing distance between telescope and shower axis a part of the observed image of the event goes beyond the field of view of the telescope, which complicates the reconstruction of the primary particle parameters.
In the present study we discuss of the distribution of the efficiency of
of such events depending on position of observed source image in the field of view in mono and stereo modes.

The experimental setup for the MPD collider at NICA, currently under construction at JINR [1], is planned to study the fundamental properties of matter in heavy-ion collisions at energies up to 11 GeV/nucleon.
This work focuses on the problem of determining the initial coordinates of Au-Au interactions at a system of center-of-mass energy of 7 GeV/nucleon and the impact of different beam pipe configurations on the accuracy of this determination. The approach used is based on the works [2], [3]. The UrQMD 3.4 event generator [4] was used for simulating interactions. The obtained results were then imported into a program implemented with Geant4 via the chromo interface [5]. These results were used to train a neural network model for solving the problem of determining the initial coordinates of ions.
Four scenarios were considered: with beam pipe wall thicknesses of 1.2, 3, 5, and 8 mm, and materials of carbon or iron. The detection areas were located 4 meters from the interaction point and consisted of rings with a diameter of 600 mm. The accuracy of the coordinate determination was measured using the square root of the mean square error (MSE).
We found that using an beam pipe with a thickness of 1 - 3 mm does not significantly affect the result and allowed us, for example, to achieve a precision for a carbon beam pipe with a thickness of 1.2 mm of √ 𝑀𝑆𝐸 ≈ 3.82 cm.
Further increasing the thickness of the beam pipe decreases the accuracy of the solution. For an iron beam pipe with a thickness of 8 mm the inaccuracy increases to √ 𝑀𝑆𝐸 ≈ 6.30 cm.
The work was supported by a grant from Saint Petersburg State University ID 95413904

References

[1] Abraamyan K. U. et al. «The MPD detector at the NICA heavy-ion collider at
JINR» // Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2011, v. 628, No 1, p. 99-102.

[2] V. S. Sandul , G. A. Feofilov F. F. Valiev. «Studying Capabilities of a Fast Monitor for Beam Collisions by Monte Carlo Simulations and Machine Learning Methods» // Phys. At. Nucl., v. 54 (2023), p. 712-716.

[3] K.A. Galaktionov, V.A. Roudnev, F.F. Valiev. «Artificial Neural Networks Application in Estimating the Impact Parameter in Heavy Ion Collisions Using the Microchannel Plate Detector Data: Physics of Atomic Nuclei» // Phys. At. Nucl., v. 86, i. 6 (2023), p. 1426- 1432

[4] Bleicher, M. and others. «Relativistic hadron hadron collisions in the ultrarelativistic quan- tum molecular dynamics model» // J.Phys. G 25 (1999), p. 1859-1896

[5] GitHub Repository
Url: https://github.com/impy-project/chromo

The isotropic light source for calibration of liquid scintillator neutrino detectors has been developed. The Monte Carlo simulation was performed to optimize its design. The satisfactory version of the source design was chosen. And the source was produced. It is currently being tested in the TAO detector. Also, the report covers the development of a primary particle generator which is able to launch large amount of photons in a single event. The generator provides flexible management of primary photons properties including their distribution type. In parallel, the report includes the results of model testing and a description of observed effects.

A Focusing Aerogel RICH detector (FARICH) detector is a valuable component of the particle identification system in the SPD experiment, improving the separation of pions and kaons in final open charmonia states (momenta below 5 GeV/c). High event rate resulting from a free-running (triggerless) data acquisition pipeline of the SPD necessitates the development of a rapid, robust software event reconstruction. In this contribution, we develop a Convolutional Neural Network (CNN)-based approach to FARICH reconstruction inspired by machine learning techniques from computer vision. The use of a flexible model trained in an end-to-end fashion allows for a more complete utilization of the input data, achieving higher quality particle separation compared with traditional approaches.

The phenomenon of neutrino oscillations emerges due to coherent superposition of neutrino mass states. An external environment can modify a neutrino evolution in a way that the coherence will be violated. Such violation is called quantum decoherence of neutrino mass states and leads to the suppression of flavor oscillations. In our previous paper [1] we presented a new theoretical framework, based on the quantum field theory of open systems applied to neutrinos. Within this framework we proposed and considered a new mechanism of the neutrino quantum decoherence engendered by the neutrino radiative decay in an electron background in an extreme astrophysical environment. In the present study we generalize our approach and investigate a novel mechanism for neutrino quantum decoherence, which arises due to the neutrino decay into a lighter neutrino state and a massless particle, as well as the inverse process of absorption of a massless particle by neutrino. We have derived the new evolution equation for the neutrino evolution that accounts for these processes. We demonstrate that studying of neutrino quantum decoherence through this evolution equation provides a unique possibility to determine or constraint the neutrino decay width.

[1] K. Stankevich, A. Studenikin, Neutrino quantum decoherence engendered by neutrino radiative decay, Phys.Rev. D 101, 056004 (2020).

Abstract:
Within the minimally extended Standard Model, neutrinos possess non-zero anomalous magnetic moments. As a result, strong magnetic fields can induce spin and spin-flavor neutrino oscillations, which may affect neutrino fluxes from astrophysical sources. We study the neutrino evolution in realistic magnetic fields and moving matter of astrophysical objects such as supernova bursts and neutron stars. For the first time, we have derived an effective Hamiltonian for neutrinos propagating in non-dipolar magnetic fields, and we have obtained appropriate probabilities for neutrino spin and spin-flavor oscillations. The importance of the work is highlighted by the construction of new Mega-Science neutrino experiments, such as JUNO, Hyper-Kamiokande, Baikal GVD and others.

Neutron response function of CeBr3 detector for

1.25-5.75 MeV neutron energy range.

Povolotskiy M.A.1,2, Sobolev Yu.G.1, Stukalov S.S.1, Bezbakh A.A.1,

Penionzhkevich Yu.E.1,2, Salakhutdinov G.Kh2, Naumov P.Yu2

1 JINR, Joint Institute for Nuclear Research, 141980, Dubna, Russia;

2 MEPhI, National Research NuclearUniversity,115409, Moscow, Russia;

E-mail: mark.povolotskiy@gmail.com

The results of measurements of neutron detection efficiency ε(En), En ≈ 1.25 ÷ 5.75 MeV for

scintillation CeBr3 detector of MULTI setup [1] are presented. The measurements of the energy dependence of efficiency ε(En) were carried out by tagged neutron method using 239Pu/9Be n-γ source.

Trigger-detector was used for registering γ-quanta Eγ = 4.44 MeV accompanied by ~60% of events of neutron emission from source 239Pu/9Be. Neutron energy values was taken from the time of flight (TOF) measurements.

The ε(En) measurements have shown that CeBr3 detector have a relatively high neutron detection efficiency which is weakly dependent on the energy values in the region En≈1.25÷5.75 MeV. For example, efficiency is ε(En)≈24,6% in energy range En=1.25÷5.75 MeV at the threshold 60 keV for CeBr3 detector (5×5×5 сm3). It was found that efficiency have strong dependence on threshold values, see Fig 1. The mean efficiency <ε> as a function of threshold values is presented in Fig 1.

In comparison stilbene detectors that are often used for neutron detection have good n-γ pulse shape separation, but sharp energy dependence of the efficiency ε(En).

This research was funded by the Russian Science Foundation, project No. 24-22-00117.

1. Zeinulla Z. et al. GAMMA-RAY SPECTROMETER ASSEMBLED FROM 9× CeBr3-NaI (Tl) PHOSWICH DETECTORS //Acta Physica Polonica B, Proceedings Supplement. – 2021. – Т. 14. – №. 4. – С. 755-760.

2. Siváček I. et al. The MULTI spectrometer for measurement of β-decay process in exotic nuclei //EPJ Web of Conferences. – EDP Sciences, 2021. – Т. 253. – С. 01003.

Theoretical and experimental investigations of neutron-rich nuclei represent one of the most fascinating and abundant sources of new information about nuclear structure. The varied properties of atomic nuclei impose significant requirements on theoretical approaches. One of the most effective microscopic methods for investigating ground-state properties is the Hartree-Fock (HF) approach, which utilizes a self-consistent mean-field based on the Skyrme energy density functional (EDF) [1]. The HF calculations with the Skyrme interactions provide a rather satisfactory description of the radii, binding energy, and single-particle (s.p.) energy of magic nuclei. However, the calculated density of the s.p. states near the Fermi level is less than what has been observed experimentally.

The s.p. states around the Fermi energy are known to be strongly affected by the nucleon effective mass profile at the surface. As shown in [2], the isoscalar correction term in the Skyrme EDF produce a surface-peaked effective mass. These dynamical correlations demonstrate that the density of states increases as the effective mass gets enhanced at the surface of nuclei [2,3]. The inclusion of the correction term in the Skyrme EDF leads to a decline in the accuracy of the binding energy description. In this work, we readjust the parameters of the Skyrme interaction and isoscalar correction term in order to reach more accurate description of binding energies and density of the s.p. states near the Fermi level [4]. As an illustration, we study impact of surface-peaked effective mass on the ground-state properties of magic nuclei 40,48Ca 132Sn, and 208Pb.

The research was supported within the framework of the scientific program of the National Center for Physics and Mathematics, topic no. 6 “Nuclear and Radiation Physics” (stage 2023-2025).

[1] M. Bender, P.-H. Heenen, and P.-G. Reinhard, Rev. Mod. Phys. 75, 121(2003).

[2] A.F. Fantina, J. Margueron, P. Donati, and P.M. Pizzochero, J. Phys. G: Nucl. Part. Phys. 38, 025101 (2011).

[3] A.P, Severyukhin, J. Margueron, I.N. Borzov, and N.V. Giai, Phys. Rev. C. 91, 034322 (2015).

[4] D.Yu. Smolannikov, N.N. Arsenyev, A.P. Severyukhin, in preparatio

We give a decomposition of the vector current matrix element, and present our analysis and study for the generalized parton distribution functions (GPDs) of spin-3/2 systems [1]. Sum rules of those GPDs and the structure functions of the systems are discussed. As a typical example, we numerically calculate the electromagnetic and gravitational form factors of the spin-3/2 baryons (like $\Delta$, $\Omega$ or other decuplet baryons) by employing a quark-diquark approach [2-4]. Lattice calculation results are considered in order to constrain our model parameters. Our calculation gives a reasonable description for the electromagnetic and mechanical properties of those spin-3/2 particles. In addition, the transversity of GPDs are also discussed [5].

       References

[1] Dongyan Fu, Baodong Sun, and Yubing Dong, Phys. Rev. D106 (2022), 116012;
arXiv: 2209.12161.

[2] Dongyan Fu, Baodong Sun, and Yubing Dong, Phys. Rev. D105 (2022), 096002;
arXiv: 2201.08059.

[3] Dongyan Fu, Baodong Sun, and Yubing Dong, Phys. Rev. D107 (2023), 116021;
arXiv: 2305.02680.

[4] Dongyan Fu, Jiaqin Wang, and Yubing Dong, Eur. Phys. J. C 84 (2024), 79;
arXiv: 2306.04869.

[5] Dongyan Fu, Yubing Dong, and S. Kumano, Phys. Rev. D109 (2024), 096006;
arXiv: 2402.11561 .

At the present time, a scintillation material $^6$Li$_2$CaSiO$_4$:Eu$^{2+}$ (LCS) is being developed at the NRC “Kurchatov Institute”. This material is designed for neutrons registration by capturing by the $^6$Li isotope. The work presents the possibility of using LCS for neutrons detection after the inverse beta decay reaction ($\bar{\nu_e} + p \rightarrow n+e^{+}$), which is widely used for antineutrinos registration in reactor experiments. It is shown that when using LCS in combination with a plastic scintillator (EJ-200, which acts as a target for antineutrinos and registers positrons), selection by pulse shape allows the signals of two scintillators to be separated, which demonstrates the possibility of using this material in antineutrino experiments.

The MPD detector at the NICA facility is under construction. One of the key
subsystems of the MPD experiment is electromagnetic calorimeter ECal.
Modules of the ECal undergo calibration using cosmic muons now. These data
were used for parameterization of the digitized SiPM signals after low pass
filter at an input of ADC. Few models of SiPM signals were tried and the
best one was found. The validity of the parameterization was tested over a
wide range of signal amplitudes. The parameterization has been used to
estimate time resolution for signals from adjacent towers. Few methods: low
threshold, constant fraction and zero crossing have been compared.

Particle identification is important in almost any high-energy physics analysis, but in some measurements such identification becomes crucial. Such analyses are the measurement of direct photon spectra and correlations, where the signal is comparable with possible contamination and the measurement of e+e- mass distribution as electrons are a tiny part of all tracks reconstructed in AA collision.
In this presentation we discuss improvements in particle identification in MPD detector at the future NICA facility that can be achieved by applying machine learning approach for particle identification in MPD tracking system and electromagnetic calorimeter ECAL.

In case of diboson production in pp collisions there is a non-negligible possibility that some events passing the final selection in data are actually from multiple overlapping hard-scatter processes occurring within the same bunch-crossing. Such events with combination of two processes associated with different primary vertices corresponds to so-called pile-up background. Its contribution should be considered in analysis of diboson production.
This study presents the overlay Monte-Carlo method for the estimation of pile-up background. The proposed approach uses two separate samples to construct pile-up events at particle-level. Then the detector efficiency is used to obtain the predicted number of such background events in the region of interest.
According to the resulting estimate the impact of the pile-up background can be either subtracted from the number of signal events or accounted as an additional systematic uncertainty.

RED-100 is a two phase detector with Xe as a target material designed to study coherent elastic neutrino nucleus scattering (CEvNS). In 2021-22 it was exposed at Kalinin NPP (Udomlya, Russia) 19 meters from the reactor core, nowadays the modification with LAr as working medium is undergoing. This poster is about reducing the specific background component. This type of background comes from spontaneous emission of single electron events (SE). Signals from coincidence of several SE signals are very similar to signals from pointlike events. Hence complex discrimination algorithms are required. We carried out a detailed simulation of the SE signals and developed two algorithms based on neural networks in order to solve this problem. Results of simulation and neural networks are shown and discussed.

Two-photon maximally entangled states or so called Bell states are the most popular objects for the study of quantum entanglement, which is the most fascinating feature of micro world. Most commonly, the tests of the entanglement are performed by measuring the polarization correlations of the corresponding photons. Such correlation has a specific behavior expressed by cosine function with some normalizing amplitude. Generally, this behavior is assigned as a feature inherent to quantum systems. Nevertheless, simple theoretical considerations and Monte Carlo simulation of classical systems reveal that similar cosine-like polarization correlations are observed also for separable photons with correlated polarizations. As the same time, the amplitude of the correlation for classical systems is a factor of 2 smaller comparing to that for quantum entangled two-photon states. These results stress the necessity of the accurate measurement of the polarimeters efficiencies. It is especially important for the study of the entangled annihilation photons through the Compton scattering, since the analyzing power of corresponding Compton polarimeters is inherently small and results in low amplitude of polarization correlations.

The monitoring of cosmic muons is an important and permanent task for low-background particle physics experiments at the surface and at shallow laboratory locations. Nevertheless, the monitoring itself at the current level of development of experimental physics techniques is rather a methodical task, so its automation seems to be necessary. This paper presents such a system for the registration of cosmic muons on the basis of plastic scintillators. The telescope is a compact portable system of three detectors, which allows to hold and change the zenith angle in automatic mode with the help of a built-in microcontroller, as well as to automate a series of measurements of the cosmic background. The results of laboratory measurements and measurements in the conditions of a nearby nuclear power reactor are presented.

The physics of positrons becomes crucial when working with radioactive isotopes like Fluorine-18, which has a proton-rich nucleus and, therefore, an excess of energy that is released by emitting positrons and neutrinos. Fluorine-18 has important applications in medical diagnostics due to its similarity to the hydrogen molecules in the human body, especially when combined with the drug fluorodeoxyglucose $^{18}FDG$. The diagnosis is performed using PET/CT equipment, which detects the annihilation photons produced by the interaction of positrons with electrons in the patient's organs or tissues. The production of this isotope is carried out in particle accelerators, such as the cyclotron. This study will focus on the production and use of Fluorine-18 in its form of $^{18}FDG$ as a radiopharmaceutical tracer for subsequent studies with PET/CT equipment, specifically the PET component.

When designing X-ray telescopes, it is essential to consider interference that may occur on the detectors. For instance, in many current telescopes, such as eROSITA from the Spectrum-Roentgen-Gamma (SRG) project, a system of magnets is positioned after the mirror assembly, which focuses particles. This magnet system is designed to deflect electrons and protons. It can deflect protons with energies up to tenths of MeV, which helps eliminate noise and extend the effective lifetime of the detector. Additionally, to protect against high-energy particles, the camera itself is surrounded by a three-centimeter copper layer, preventing residual noise from penetrating the system.
A similar task was set for a new telescope with parameters comparable to those of eROSITA, for which a model of the magnetic field was constructed and calculated, allowing the detectors to be shielded from unwanted influences.

The NA64 experiment at the CERN SPS is designed to search for dark photons in events with missing energy. The most studied production mechanism is dark Bremsstrahlung through a vector mediator. Bremsstrahlung photons can convert to hard vector mesons in exclusive photoproduction processes, which then decay to dark matter (DM). The vector meson decays invisibly to DM via mixing with the dark photon. The possibility of rho0 invisible decay will be shown.

The DANSS detector is placed under the reactor core of Kalinin NPP (at distances 10.9–12.9 m) and collects up to 5000 antineutrino events per day. One of the main goals of the experiment is to scrutinize the sterile neutrino hypothesis. A large fraction of allowed parameter space was excluded by DANSS: for some values of Δm$^2$, the exclusion goes up to $\sin^2(2\theta)<0.01$, which had become the best in the world. In addition, the combination of a favorable placement of the detector near the reactor and large acquired statistics allows to investigate other scenarios of electron antineutrino disappearing. This poster reports on probing the Large Extra Dimensions (LED) hypothesis in the simplest approach of only one additional dimension. This theory describes particles oscillations to hidden, finite-size additional dimensions and provides sensitivity to neutrino mass. Report covers MC generation for different LED parameters, study of experiment sensitivity for oscillation to LED, and investigation of exclusion areas in the phase space in the coordinates of $a$ and $m_0$—size of hidden dimension and mass of the lightest neutrino.

Bosonic dark matter search results with neutrino detector iDREAM at Kalinin Nuclear Power Plant are presented. Using accurate data on composition of the active core of VVER-1000 nuclear reactor and fission fractions of primary fissile isotopes, the $\gamma$-radiation energy spectrum in the active core is calculated. Assuming that the dark bosons can be produced in the active core via $\gamma$-scattering on electrons and can be detected via an inverse process inside the iDREAM detector, experimental bounds on the coupling constant $g_X$ between the dark boson and Standard Model charged current are derived.

The νGeN experiment aims to study coherent elastic neutrino-nucleus scattering and antineutrino electromagnetic properties. The experimental setup is deployed at the Kalinin Nuclear Power Plant. The data is collected with the help of a 1.4 kg high purity germanium detector located at about 11 meters from the reactor core. This poster presents the estimate of the sensitivity of the νGeN experiment to antineutrino magnetic moment and charge. The estimate is performed based on the energy deposition spectrum corresponding to 69.2 days exposition time in the reactor OFF regime.

The semi-inclusive deep inelastic scattering (SIDIS) of a lepton on a polarized proton provides a means of studying the internal structure of the proton. This scattering gives an observable, the Sivers asymmetry, which can be measured for positive and negative pions productions within the scattering event. This measurement allows access to the Sivers parton distribution function (PDF).

In this study, we have devised a methodology for calculating the Sivers asymmetry using PYTHIA8 and modified in this report StringSpinner plugin for charged pions in the muon SIDIS on a polarized proton. To validate the developed method, we present a comparison between the calculated Sivers asymmetries as a function of the Björken variable $x_{\text{Bj}}$ and the experimental values obtained by the COMPASS experiment.

We acknowledge support from Russian Ministry of Education and Science. State assignment for fundamental research (code FSEG-2024-0033)

The results of the development of a DAQ (data acquisition) system for collecting and processing data from Flash ADC and TDC (time to digital converter) blocks by Caen are presented. A comparative analysis of the speed characteristics of data transmission over the Optical link and VMEbus bus of boards of different versions with different initial configurations of internal memory buffers, as well as by type of connection to a personal computer, was carried out. A variant of organizing data collection is shown, both in single block mode and in multiple connection mode via the Caen v2718-v3718 controller using an interrupt mechanism. The approach of client-server interaction between the main DAQ system and the remote user interface is described. A brief overview of intermediate data caching, methods and types of writing them to the main storage medium is given. A brief overview of the implemented functionality for processing accumulated spectra is given, including calibration tools, automatic detection of peaks in a given area and point-to-point spectrum investigation.

The opaque scintillator detector is a novel concept for a new generation of position-sensitive detectors. The main idea is to localize the light near the point of its scintillation via the scattering medium. The first and only published results by the LiquidO collaboration are based on the usage of an opaque liquid scintillator.
Our approach suggests the usage of media based on solid granular organic scintillator and an array of WLS fibers with SiPMs as photodetectors. The report describes the new results obtained during the beam test of different configurations of scintillating and scattering media with external proportional chambers as a tracking system. The results of media comparison and estimation of track reconstruction accuracy are presented.

In 2019, as part of the development of the TAIGA (Tunka Advanced Instrument for cosmic rays and Gamma Astronomy) astrophysical complex, construction of the TAIGA-Muon scintillation facility began in addition to the existing Tunka-Grande system. The main objective of these systems is to study the energy spectrum and mass composition of cosmic rays in the energy range of $10^{15}–10^{18}$ eV, as well as to search for gamma radiation in the same energy range. Original detectors have been developed for the TAIGA-Muon facility that use light guides with spectrum re-emitters to collect light on the PMT. Currently, 5 out of 10 planned stations (clusters) have been deployed. Each station contains a ground part for detection of the charged component of the EAS and an underground part for the muon component registration.
The report, firstly, presents the objectives and status of the facility, a description of the design of scintillation counters and clusters, as well as the structure of data collection, time synchronization, control and monitoring systems. The results of the study of EAS with an unusual spatiotemporal structure are presented. It is assumed that the nature of the pulses with a multipeak structure and multipulse signals observed in the Tunka-Grande detectors is associated with random coincidences from single atmospheric muons, PMT afterpulses, and features of the spatiotemporal structure of the EAS. The report also presents the results of a study of the joint operation of the Tunka-Grande and TAIGA-HiSCORE setups in order to search for sub-PeV gamma quanta. Estimates are made of the expected number of registered gamma quanta from the Crab Nebula. The work was supported by the Russian Science Foundation, project 23-72-00054.

By periodically varying the temperature of a pyroelectric single crystal under vacuum conditions, a compact charged particle accelerator can be created [1]. In addition to the single crystal, this also requires a grounded target, which acts as the second electrode in the acceleration scheme. This type of accelerator can be described as quasi-electrostatic. In various modes, this compact device can serve as a monoenergetic source of non-relativistic electrons, ions, X-rays, and even neutrons [2-4].

This paper discusses the phase characteristics, emittance, and focusing of such an accelerator. The study was conducted both experimentally and through numerical simulation. Issues related to avalanche breakdown, which are significant for practical applications, and stability and reproducibility of electron beams are also discussed.

The work of P.G. Shapovalov and A.N. Oleinik was financially supported by a Program of the Ministry of Education and Science of the Russian Federation for higher education establishments, Project No. FZWG-2020-0032 (2019-1569).

References

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The light nuclei 12C and 6Li used as target and projectile nuclei in the many experimental studies of the nuclear reactions, including Flerov Laboratory of Nuclear Reaction (JINR). The study of the structure of these nuclei is necessary for theoretical description of such reactions. Wave functions of the ground state of the 12C and 6Li nuclei in the alpha-cluster model are calculated using hyperspherical functions [1]. Cubic spline interpolation is applied for solving hyperradial equations [1]. The alpha-alpha interaction in the 12C nucleus is changed in comparison with well-known Ali-Bodmer potential [2]. As a result, the energy of separation to alpha-particles and the charge distributions were calculated and agreement with experimental data [3‒5] was obtained (Fig. 1). The alpha-cluster model may explain the strong oblate deformation of the 12C nucleus (with β2 = ‒0.59 [6]). In addition, the shell model of the deformed nuclei is used to calculate the nucleon states in the 12C nucleus for comparison against alpha-cluster model.

1. V.V. Samarin, Eur. Phys. J. A, 2022, V. 58. 117.
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6. Chart of nucleus shape and size parameters, http://cdfe.sinp.msu.ru/services/radchart/radmain.html.

The SuperFGD (Super Fine-Grained Detector) is a part of ND280 near
detector complex for T2K and Hyper-Kamiokande experiments. The
SuperFGD is a fully active and highly granular scintillator neutrino
detector. It consists of ∼2 million scintillation cubes, which allow
reconstruction of particles going in all directions. A good
understanding of SuperFGD response is crucial for detailed Monte-Carlo
simulations and further physics studies. This poster covers selection
of atmospheric muons stopped inside the sensitive volume of the
detector including their decays. Muons were selected by applying
geometrical constraints and searching for subsequent electron or
positron. The reconstructed spectrum of the Michel e-/e+ is useful for
energy scale determination. Bragg’s curve built using muon energy
release along its track is sensitive not only to energy scale but also
to the nonlinear effects: Birks coefficient and Cherenkov radiation
intensity. Reconstruction of Compton electrons following positron
annihilation allows to evaluate an effective low energy threshold.

The minimum analytical model describing the neutrino radiation at conditions of core-collapse supernova, is considered. We find that such model contains four parameters. Each of these parameters depends on the radial coordinate and time. In addition, the numerical values of individual parameters have a large spread of values and significantly depend on the hydrodynamics of the explosion. Thus, it is important not only for finding neutrino parameters within the one of the supernova explosion models, but also the their generalization for other explosion models. For this purpose, we use results of the one-dimensional simulation of neutrino propagation, performed self-consistently with hydrodynamics in Prometheus-Vertex code. Both neutrino parameters and characteristic hydrodynamic scales were obtained for progenitor from 11.2 to 25 Solar masses at different times after a bounce. It is shown, that in the outer part of the supernova the angular distribution parameter of the neutrino correlates with the protoneutron star radius. In this region, the energy parameters can be considered as constant in radial coordinate. Fourth parameter can be fixed by the supernova neutrino luminosity. Thus, the proposed approach allows to obtain the radial dependence of the modeling parameters of neutrino radiation in various explosion models. Moreover, in the outer part the neutrino radiation is determined by four global parameters of the supernova: the protoneutron star radius, the neutrino luminosity, average neutrino energy and the width of the spectral distribution.

The work is supported by the Russian Science Foundation (Grant No.
24-22-00417, https://rscf.ru/project/24-22-00417/)

To obtain the neutrino parameters in core-collapse supernova we use the results of a one-dimensional simulation of neutrino propagation, performed self-consistently with hydrodynamics in Prometheus-Vertex code. As in most modern model of neutrino propagation in supernova, in this numerical code the moments approach is applied for calculation of neutrino transport. This method is based on the separation of neutrino energy range to bins and allows to get us only the integral value of neutrino specific intensity in them. In this case, the simplest way to find the neutrino radiation parameters is to use total integral energy moments. But this approach does not allow to obtain neutrino radiation parameters for some analytical models, for example, for a popular Fermi-like approximation of the neutrino energy spectrum. Because of that, we use method based on the minimization of the functional, which determinates the deviation of integral value of the model spectrum from the data performed with Prometheus-Vertex code. This approach of finding of neutrino radiation parameters allows us to more accurately approximate the data, and it can be used in case when the approach of energy moments are not applicable.

The Large Volume Detector located in the Gran Sasso Laboratory, Italy, has been operating in the stellar core collapse neutrino search program since 1992. Based on 32 years of detector data, an experimental constraint on the frequency of neutrino bursts from gravitational collapses of stars in the Galaxy has been obtained: less than 1 event in 13.9 years at a 90% confidence level. At an average depth of 3650 m w.e., the detector registers atmospheric muons with an average energy of 280 GeV in the angular range of 0 – 90. The detector background in the low-energy range from 0.5 to 3 MeV is the natural radioactivity of the soil, the iron structures of the detector, and radon decay products in the room air. Variations in gamma quanta and muons are continuously monitored as the detector background when searching for neutrinos from supernovae. The paper presents the latest results of the analysis of the experimental data from the LVD detector.

Currently, there is a wide variety of different neutrino oscillation experiments which collect data of neutrino interactions before and after their oscillations. To process and analyze these data it is necessary to have a reliable and highly efficient computing software. GNA (Global Neutrino analysis) is a software developed at JINR to carry out neutrino oscillation analysis of various experiments such as reactor, accelerator, atmospheric, and solar ones. It has been actively developing to provide global fit of data taken from different types of experiments. This poster will show in details the features and benefits of using the GNA software to perform neutrino oscillation analysis.

This report shows how the current models of reactor antineutrino energy spectra affect the estimates of the count rate for coherent elastic neutrino-nucleus scattering (CE$\nu$NS) in the RED-100 experiment. The reactor antineutrino spectrum consists of contribution from 4 main (parent) isotopes $^{235}U$, $^{238}U$, $^{239}Pu$, $^{241}Pu$, taken with partial coefficients on the burn-up moment. We analyze and compare the spectra-averaged differential cross-section for each model and compared the resulting CE$\nu$NS count rate in RED-100 at a distance of $\sim$19 meters from reactor core at the Kalinin nuclear power plant (KNPP). The calculations performed show the difference between count rate estimations for each model and the corresponding constraints on CE$\nu$NS cross-section amplitude. It is shown that the reactor high energy antineutrinos make a significant contribution to the prediction value.

Based on new measurements of the ratio of cumulative spectra of $\beta$-particles ${}^{235}\text{U} / {}^{239}\text{Pu}$ performed at the Kurchatov Institute (KI), the cumulative spectra of $\beta$-particles and $\bar{\nu}_{e}$ fission products of ${}^{235}\text{U}$, ${}^{239}\text{Pu}$ and ${}^{238}\text{U}$ isotopes have been updated. The obtained spectra $\bar{\nu}_{e}$ ${}^{235}\text{U}$, ${}^{239}\text{Pu}$ and ${}^{238}\text{U}$ KI are compared with similar spectra of the Huber-Mueller (HM) model, and the spectra of $\beta-$ particles of KI are compared with the spectra of $\beta-$ particles of ${}^{235}\text{U}$, ${}^{239}\text{Pu}$, measured at the Institute Laue-Langevin (ILL), and the spectrum of $\beta-$ particles ${}^{238}\text{U}$ -- at the Technical University of Munich (TUM). The calculated inverse beta-decay yields are in good agreement with the reactor neutrino experiments data.

The Wheeler–DeWitt geometrodynamics, which was the first attempt to develop a quantum theory of gravity, faces some problems, such as the problem of time or the interpretation of the wave function. In this work, as an alternative to Wheeler–DeWitt quantum geometrodynamics, we consider the extended phase space formalism. Within this framework, one can derive the Schrödinger equation, which describes the evolution of a physical object over time and incorporates gauge degrees of freedom. This work generalizes the existing quantization method for models with a finite number of degrees of freedom, as proposed by Cheng, and enables us to derive the Schrödinger equation for systems described by field functions. As a result of our research, the integro-differential Schrödinger equation for a centrally symmetric model was obtained, its structure was studied, and its solution was interpreted. Additionally, the analytic solutions of the Wheeler-DeWitt equation and the Schrödinger equation were compared in the gauge condition N=1/V, corresponding to the Schwarzschild solution, and in the gauge condition N=1, corresponding to the Tolman solution.

The main goal of the NA64 experiment is searching for sub-GeV dark matter production mediated by a dark photon A' or light dark boson Z'. Dimuons are used to check the accuracy of the Monte-Carlo simulation of the NA64 setup based on the Geant4 package. They also represent a background source in the dark sector search.

For further investigation of neutrino oscillations in the T2K
experiment, a 3D segmented SuperFGD detector is constructed. It
consists of 2 million scintillation cubes of 1 cm3 size, with wavelength-
shifting (WLS) fibers along three orthogonal directions. Each fiber is read
out by a Hamamatsu Multi-Pixel Photon Counter S133060-1325PE. The
detector main goals are to reduce systematic uncertainties and increase
the sensitivity of a search for CP-violations in the lepton sector.
Preliminary results of time resolution using upstream and side fibers
were received with cosmic run after implementing time offset and time
walk calibration. It was obtained that the time resolution is $\sigma\simeq 1.17$ ns for
one fiber readout and a threshold of 40 photoelectrons. The main
calibration parameters, the light yield, and the attenuation length
obtained during the detector commissioning with cosmics and in the T2K
neutrino beam will be also presented in this report.

We present a further development of the Modified Monte Carlo Glauber model (MGM) [1],[2], which takes into account at the given impact parameter of heavy nuclei interaction, for each nucleon, the fraction (k) of energy loss, arising during the consecutive inelastic nucleon-nucleon collisions due to multiple production of particles. The one-parameter model also takes into account, at each step of the consecutive binary collisions, the corresponding decreases of the inelastic cross section value and of the charged particles yield. We updated the MGM code for the collisions of the deformed nuclei and for the possibility to reveal the contributions by different certain numbers of binary collisions to the total charged-particle multiplicity.
This study was motivated by the results [3] on the first measurements of the charged-particle multiplicity density and total charged-particle multiplicity in Xe–Xe collisions at a centre-of-mass energy per nucleon–nucleon pair of $\sqrt{s_{NN}} = 5.44$ TeV. The strong effect of violation of scaling of the total charged-particle multiplicity normalized by the number of nucleons-participants  was observed in [3] in the region of very central Xe–Xe and Pb-Pb collisions. We show for both undeformed and deformed nuclei, that our one-parameter model successfully explains the observed deviation of scaling with the number of nucleons-participants at the LHC energies.

The authors acknowledge Saint-Petersburg State University for a research project 95413904

[1] Feofilov G., Ivanov A. // Journal of Physics G CS. 5. 2005. P. 230-237

[2] Feofilov G., Seryakov A. // AIP Conference Proceedings. 2016.1701.1. P. 07000

[3] AlLICE Collaboration, //Physics Letters. B 790.2019. 35–48

G.A. Askaryan had shown in 1960s [1,2] that the interaction of high-energy particles with the rather dense dielectric medium should form the negative charged cascades moving with superluminal velocity in the medium. This Askaryan’s effect is laid on the basis of the radio-astronomical method for detecting ultra-high-energy neutrinos, proposed later by R.D.Dagkesamansky and I.M. Zheleznykh [3]. This report provides a brief overview of the application of this radio astronomy method to search for Cherenkov radio bursts from the Moon. Some results of the search for such radio bursts on the meter wave radio telescope BSA FIAN are presented.

Superfluid He-4 can serve as a tool for neutrino [1] and dark matter detection [2]. Low-energy neutrino interaction with superfluid He-4 can take place in the form of coherent elastic neutrino-atom scattering (CEvAS) [3] - a process that has not been observed so far. The first experimental study of CEvAS is under preparation in the National Center for Physics and Mathematics in Sarov [4]. Using a high-intensity tritium neutrino source and a superfluid He-4 detector, it will have a rich potential to test the neutrino physics of Standard Model and beyond it at unprecedentedly low energies. For example, one of the observable effects of beyond-Standard-Model physics in CEvAS can be neutrino millicharge and magnetic moment [5]. In our work we develop a theoretical approach for studying neutrino interaction with a superfluid He-4 by taking into account single quasiparticle production in a superfluid He-4 target upon tritium neutrino scattering. In particular, we show that such collective effects drastically influence the neutrino scattering cross section at energy transfer of the order of 1 meV and less.

[1] R.E. Lanou, H.J. Maris, and G.M. Seidel, Detection of solar neutrinos in superfluid helium, Phys. Rev. Lett. 58 (1987) 2498.

[2] You, Y., Smolinsky, J., Xue, W., Matchev, K., Saab, T., Gunther, K., and Lee, Y. Signatures and detection prospects for sub-GeV dark matter with superfluid helium. JHEP 2023(7) (2023)  1-31.

[3] M. Cadeddu, F. Dordei, C. Giunti, K. Kouzakov, E. Picciau and A. Studenikin, Potentialities of a low-energy detector based on 4He evaporation to observe atomic effects in coherent neutrino scattering and physics perspectives, Phys. Rev. D 100 (2019) no.7, 073014 [arXiv:1907.03302 [hep-ph]].

[4] А.А. Yukhimchuk, А.N. Golubkov, I.P. Maximkin, et al., Physics of hydrogen isotopes, FIZMAT 1 (2023) 5 (in Russian).

[5] G. Donchenko, K. Kouzakov, and A. Studenikin, Elastic neutrino-atom scattering as a probe of neutrino millicharge and magnetic moment, JETP Lett. 117 (2023) 879.

Neutrino oscillations have been actively studied for the last few decades. At the moment, the unknown parameters of the theory are the neutrino mass ordering and the phase of CP violation in the lepton sector. One of the ways to increase the sensitivity to these parameters is the combination the results of several experiments. For many years phenomenologists have been doing such unification with certain approximations taken into account, so called global fits. Recently, experiments themselves started to produce the joint fits. In the past year T2K + SuperK and T2K + NOvA announced their first results.
In this talk status of both joint and global analyses will be discussed as well as their future prospects.

The NOvA experiment is a long-baseline neutrino experiment designed to study the oscillation behavior of neutrinos and antineutrinos utilizing Fermilab’s Megawatt-capable NuMI neutrino beam. NOvA has been collecting data for 10 years from two functionally identical tracking calorimeter detectors, which are situated off the NuMI beam axis and separated by 810 km. The experiment’s construction allows us to observe muon (anti)neutrino disappearance and electron (anti)neutrino appearance. Therefore, we can obtain precision measurements of oscillation parameters, such as the mass splitting $\Delta m^{2}_{32}$​ and the mixing angle $\theta_{23}$​, as well as get closer to understanding the matter-antimatter asymmetry in the universe. In this talk, an overview of the NOvA experiment and its latest results will be presented.

The analysis presented in this work aims at the study of heavy neutrinos (N) with masses $< 493\,~\text{MeV/c}^2$ produced in charged kaon and pion decays and subsequently decaying in the T2K off-axis near detector ND280. Two- and three-body decay modes are considered:

$N \rightarrow l_{\alpha}^{\pm} \pi^{\mp}, \ N \rightarrow l_{\alpha}^{+} l_{\beta}^{-} \nu (\bar{\nu}),~\text{where (}\alpha, \beta = e, \mu)$

Time Projection Chambers (TPCs) volume is used to reduce background from neutrino interactions. The T2K data accumulated in years $2010-2018$ will be used. First estimations of signal selection efficiency show improvement in comparison with previous results [1,2]. Improvement of current upper limits on mixing elements between heavy and active neutrinos is expected due to increased statistics, inclusion of pion decays and additional heavy neutrino three-body decay channels. In this talk, systematic uncertainties, background estimations and expected sensitivity towards mixing elements will be presented.

The work is supported by Russian Science Foundation (RSF) grant №22-12-00358. The author is grateful for the assistance given by Y. Kudenko, A. Izmaylov and T2K collaboration members.

1. Abe K., et al. "Search for heavy neutrinos with the T2K near detector ND280." Physical Review D 100.5 (2019): 052006

2. Antel C., et. al. "Feebly Interacting Particles: FIPs 2022
   workshop report". arXiv.2305.01715, pp. 278-281

The long baseline neutrino oscillation experiment T2K [1] is aiming at searching for CP violation in the neutrino sector and precision measurements of neutrino oscillation parameters. T2K has obtained results indicating CP violation with more than 90% confidence level [2]. In the T2K experiment, the neutrino beam generated at J-PARC is measured at the near detector ND280 located 280m downstream from the proton target. The ND280 was recently upgraded to reduce systematic errors and improve measurement of the neutrino beam before oscillations. A new scintillation tracker Super Fine-Grained Detector (SuperFGD) consists of about 2 million scintillator cubes, each of 1 cm3 [3]. The signal from each cube is read out by three orthogonal WLS fibers and detected by micropixel photosensors MPPC. The detector has a high light yield for charged particles, a good time resolution and a low detection threshold. SuperFGD is a more efficient neutrino detector which selects high angle and low momentum particles, accumulate larger sample of neutrino interactions, and detect neutrons. SuperFGD was installed in the ND280 pit at J-PARC in October 2023, and started full data taking in June 2024. The calibration of SuperFGD readout channels using LED system and cosmic muons will be presented. Detection of muon neutrinos in SuperFGD through charged current in the T2K neutrino beam will be presented and discussed. The emphasis will be put of reconstruction of muons and stopped protons in SuperFGD.

Supported by the RSF grant # 24-12-00271

[1] K.Abe et al. The T2K Experiment, Nucl. Instrum. Meth. A659 (2011) 106–135.

[2] K.Abe et al. Constraint on the matter–antimatter symmetry-violating phase in neutrino oscillations, Nature 580 (2020) 7803, 339-344.

[3] A.Blondel et al. A fully active fine-grained detector with three readout views, JINST 13 (2018) 02, P02006.

In the P2O (Protvino-to-ORCA) experiment, it is planned to direct a neutrino beam from the U-70 proton accelerator (Protvino, Russia) to the Mediterranean Sea to detect neutrinos with the deep-sea ORCA detector created near the French coast. The purpose of these experiments is to determine the neutrino mass hierarchy and search for CP-violation in the lepton sector. Various options of the construction of the corresponding neutrino channel at the U-70 accelerator were considered earlier.
In this report different types of uncertainties in the experiment and the contribution of each of them to the CP-violation phase measurement error are studied. This will help to understand their importance and make possible in future to develop the optimal design of the planned long-baseline experiments (the type and characteristics of the beam, detectors, necessary integral luminosity). We also calculated the sensitivity of the P2O experiment in the measurement of the CP-violation phase in the lepton sector for the previously considered neutrino beams. The choice of the optimal variant of the neutrino beam ensuring the maximal sensitivity of the P2O experiment is carried out.

Low-background technique and physics at BNO

The possibility of active neutrinos oscillation into the sterile neutrinos is one of the most discussed topics of neutrino physics nowadays. Experimental evidences favoring for the oscillations were obtained from radiochemical gallium-germanium (Ga-Ge) experiments SAGE, GALLEX/GNO and BEST. Especially the latest data from BEST experiment have revealed convincingly, at the level of 5σ, a 20% deficit of the neutrinos detected from an artificial neutrino source – the effect called as “gallium anomaly".
This deficit of the neutrinos was established, in particular, by taking into the calculations the half-life value of 71Ge radionuclide. Meanwhile, the half-life value of 71Ge, which is considered to be relevant at present days (T1/2=11.43 days), was obtained in 1985 and this value diverges significantly (up to ~10σ) from the results of earlier measurements performed in 1950s. By application in the calculations the somewhat greater 71Ge half-life value than the accepted one, the gallium anomaly can be eliminated or its statistical reliability can be significantly reduced.
The aim of the presented work is to verify the validity of 71Ge half-life value determined previously. The 71Ge isotope was obtained by the irradiation of natural germanium wafer in the neutron beam of PNPI accelerator. Spectra of 71Ge were measured with several Si and Ge detectors during with the exposure periode over six months. More details about the measurement procedure and the obtained experimental results will be presented at the Conference.

The highly segmented DANSS anti-neutrino scintillation detector is located at the Kalinin NPP and collects up to 5000 antineutrino events per day. The reactor power was measured using the inverse beta-decay (IBD) event rate during 7.5 years with an accuracy of 1.3% in 3 days and with the relative systematic uncertainty of less than 0.8%. The report will present the measured dependence of the antineutrino spectrum on the composition of reactor fuel. The measured ratio of cross-sections 235U/239Pu will be presented. The 239Pu fission fraction was measured during 7 years of the reactor operation using a fit of the measured IBD positron spectrum with model predictions for different isotopes. Taking into account the absolute antineutrino counting rates, the parameters of a hypothetical sterile neutrino region was extended above $\Delta m^2$ > 5 eV$^2$, where there are indications of the existence of a sterile neutrino in the BEST and Neutrino-4 experiments

Ensembles of He and H isotopes can be studied with unique completeness and resolution in nuclear emulsion layers longitudinally exposed to relativistic nuclei [1,2]. Determination of the invariant mass of their pairs or triplets by emission angles in the velocity conservation approximation is sufficient to identify a number of unstable states – $^8$Be(0$^+$), $^8$Be(2$^+$), $^9$B, $^{12}$C(0$^+_2$), $^{12}$C(3$^-$), $^6$Be.

The BECQUEREL experiment [3,4], using this approach, is aimed at searching for the α-particle Bose-Einstein condensate (αBEC), an unstable of S-wave α-particle state. $^8$Be(0$^+$) is associated with 2αBEC, and $^{12}$C(0$^+_2$) or the Hoyle state with 3αBEC. In the relativistic fragmentation of heavy nuclei, an enhancement of $^8$Be, $^9$B and $^{12}$C(0$^+_2$) is detected, suggesting their synthesis in the fusion of associated α-particles. The focus of the search is the 4αBEC state of $^{16}$O(0$^+_6$) at 660 keV above the 4α threshold, decaying into α$^{12}$C(0$^+_2$) or 2$^8$Be. In this context, the status of the analysis of α-particle fragmentation in a nuclear emulsion exposed to $^{84}$Kr nuclei at 950 MeV per nucleon is presented. Secondary stars produced by relativistic neutrons are observed in the nucleus fragmentation cone [4]. The neutron average energy in the parent nucleus system is estimated to be 1.3 MeV [5].

The αBEC search leads to the study of nuclear matter in the region of temperature and density from red giants to supernova. It is characterized by the ratios of $^{1,2,3}$H and $^{3,4}$He. Nuclear emulsion layers exposed to heavy nuclei of several GeV per nucleon at the NICA accelerator complex are optimal for identifying H and He isotopes by multiple scattering, searching for unstable states, and assessing neutron accompaniment. An exposure to $^{124}$Xe nuclei of 3.8 GeV per nucleon, performed at the NICA/Nuclotron accelerator complex, allows the use of proven approaches. Parameters of the beam are determined using the CR-39 track detector by direct crater counting on the Olympus BX63 microscope.

[1] P.I. Zarubin, Lect. Notes in Phys. 875, Clusters in Nuclei, Volume 3. Springer Int. Publ., 51 (2013); arXiv: 1309.4881.

[2] D.A. Artemenkov et al., Eur. Phys. J. A 56 250 (2020); arXiv: 2004.10277.

[3] A.A. Zaitsev et al., Phys. Lett. B 820 136460 (2021); arXiv: 2102.09541.

[4] D.A. Artemenkov et al., Phys. At. Nucl. 85, 528 (2022); arXiv: 2206.096.

[5] A.A. Zaitsev et al., Phys. At. Nucl. 86, 1101 (2023); arXiv: 2307.16465.

The interaction of deuteron and proton beams with light nuclei is characterized by a wide variety of reactions of interest for both technical and fundamental applications.
The reaction $^7Li(d,n)α$ is characterized by a high neutron yield and high neutron energy (13.125 MeV), which is relevant for conducting radiation tests of modern materials and equipment.
For the reaction $^{11}B(p, α)αα$, reliable knowledge of the cross section is relevant for proton therapy of cancer, the implementation of the boron-proton fusion reaction in thermonuclear energy and the study of the mechanism of primary nucleosynthesis.
Despite the long-standing interest in these processes, the experimental data on cross-sections vary greatly among different authors, and for a number of reactions, cross-section values ​​are not available in the databases.
At the Institute of Nuclear Physics of the Siberian Branch of the Russian Academy of Sciences, at the VITA accelerator neutron source, the cross-sections of the following reactions were measured experimentally in the energy range of 0.3-2.3 MeV:
- $^6Li(d,α)α$, $^6Li(d,p)^7Li$, $^6Li(d,p)^7Li^*$,$^7Li(d,α)^5He$, $^7Li(d,nα)α$, $^{10}B(d,α_0)^8Be$, $^{10}B(d,α_1)^8Be^*$, $^{10}B(d,p_2)^9Be^*$, $^{11}B(d,α_0)^9Be$, $^{11}B(d,α_2)^9Be^*$
- $^{11}B(p,α)αα$, $^{11}B(p,α_0)^8Be$, $^{11}B(p,α_1)^8Be^{**}$

The study was supported by the Russian Science Foundation grant No. 19-72-30005, https://rscf.ru/project/19-72-30005/.

New experimental results were obtained for the fragmentation of 230 MeV/nucleon 56Fe on 9Be, 27Al, 64Cu targets. The experiment was carried out on the FRAGM setup at TWA heavy ion facility. The detector FRAGM allows to measure the fragment momentum with high accuracy at an angle of 3.5 degrees [1,2]. It was found that the momentum distribution of light fragments in the rest frame of the incident nucleus has a double-humped structure, which is not typical for fragmentation processes. This paper contains a phenomenological description of the magnitude of momentum peak splitting, which is especially manifested in proton spectra and decreases for heavier fragments. Experimental results are compared with data obtained on the FRS-GSI setup [3] and with the predictions of different models of nucleus-nuclear collisions. The possible source of this phenomenon is connected with coulomb effects in the asymmetric fission.

Bibliography

[1] B.M. Abramov et al., Phys.Atom.Nucl. 85, 1541 (2022).

[2] A.A. Kulikovskaya et al., Phys.Atom.Nucl. 85, 466 (2022).

[3] P. Napolitani et al., Phys.Rev. C 70, 054607 (2004).

The formation of the multi-neutron systems 2n and 3n was studied in the reactions of stopped pion absorption by 9Be nuclei. Measurements were carried out at low energy pion channel of LANL using two-arm multilayer semiconductor spectrometer. The bound states of 2n and 3n have not been found. In the missing mass spectrum of the reaction 9Be(pi-, t4He), a peak was observed near the threshold, which is due to the formation of the s-wave virtual state of the dineutron. Indications of the existence of two states of the 3n with resonant parameters (Er ≈ 5 MeV, Г < 3 MeV and Er ≈ 13 MeV, Г < 3 MeV) were first obtained in the reactions 9Be(pi-, d4He) and 9Be(pi-, t3He). Comparison with theoretical and experimental results obtained by other authors was performed.

In our previous publications [1-4] we presented experimental evidences of rare ternary decay mode of low excited heavy nuclei. Essential feature of this process is that some of the fission fragments (FFs) born during binary fission undergo a break-up, while they pass a solid-state foil. This break-up is delayed and occurs after the binary fission of the mother system. It is reasonable to think of such specific FFs as formed in the shape-isomer states. The break-up is due to the FF inelastic scattering in the foil medium. Strong indication was obtained of clustering of the mother system at the stage of binary fission and clustering of the intermediate fragment which undergoes further break-up. Deformed magic and semi-magic nuclei play role of clusters. We especially discuss the manifestation of the N=32, 34 subshell closures in the light products of the break-up.

References

1. Yu.V. Pyatkov et al., Eur. Phys. J. A 45, 29 (2010).

2. Yu.V. Pyatkov et al., Eur. Phys. J. A 48, 94 (2012).

3. Yu.V. Pyatkov et al., Phys. Rev. C 96 (2017) 064606.

4. Yu. V. Pyatkov et al., Physics of Atomic Nuclei, 85, 763 (2022)

In our previous publications [1–3], a very specific effect, unknown in the past, was discussed, namely a break-up of the fission fragment while it passes through a solid-state foil. The fraction of the fragments which undergo the break-up is supposed to be born in the shape isomer states. The bulk of the results were obtained in the frame of the so-called missing mass experimental method when only one of two partners of the break-up is detected by the spectrometer. The difference between the total mass of the detected fragments and the mass of the mother system serves a sign of at least ternary decay. Alternative, so called” double-hit” approach lets obtain more direct information about the process. By definition, the double-hit registration approach means that two fragments were detected in the same PIN diode during one registration gate of 200 ns length. If a minimum time interval between their time stamps is less than 30 ns a pile-up of the signals take place. Restoring original signals from pile-up is discussed.

6He is one of the simplest nuclei with a halo in the ground state 0+; its study has received significant theoretical attention [1]. In [2], an assumption was made about a halo-like structure in the isobar-analog state of the 3.563-MeV, 0+ 6Li state. This structure is a spatially extended halo-like structure with an alpha particle core and a proton and neutron surrounding it. One of the last theoretical results is the calculations within the ab initio NCSM (no-core shell model) [3]. Calculations showed that the radius of the ground state of 6Li, within the error limits, coincides with the radius of the 3.56 MeV state of 6Li.
Our group is studying the 6Li nucleus, especially its second excited 3.563-MeV, 0+ state for a long time. One of the first results was the Modified diffraction model (MDM) application [4] to existing literature data. The literature differential cross sections for inelastic scattering of 3He + 6Li with excitation of the 2.19 MeV state, 3+ at energies of 34 and 72 MeV and 3.56 MeV, and 0+ state at energies of 24.6 and 27 MeV were analyzed. It was shown that the radius of the 2.19 MeV, 3+ state, within errors, coincides with the radius of the ground state, and the radius of the 3.56 MeV, 0+ state is 2.5 ± 0.2 fm [4] and, within errors, coincides with the radius of 6He, which allows for the possibility of the presence of a halo (proton-neutron, and in some works called tango-halo) [5]. The obtained value is less than the previously predicted radius of this state of 2.73 fm [2].
During last year’s we are adopting “Distorted Wave Born Approximation” (DWBA) to make some qualitative estimations on radii of 6Li excited states. Two new experiments were done: 1) 7Li (d, t)6Li experiment was performed on the deuteron beam of the U-150M cyclotron at the Institute of Nuclear Physics (Almaty, Republic of Kazakhstan) at an energy of 14.5 MeV; 2) 10B(7Li,6Li)11B experiment was performed on the 7Li beam of the U-400 accelerator beam of the FLNR JINR, Dubna at energy of 58 MeV. The angular distributions for the ground and first excited states of 6Li were obtained. The experimental data were analyzed within the framework of the DWBA. We obtained radial dependences of the form factors and the ANC values for 6Lig.s and 6Li (3.56 MeV) states. The obtained values of the ANC for the 6Lig.s. and 6Li(3.56 MeV) states are similar to those in the literature. This fact confirms correctness of our DWBA analysis. Comparison of the radial dependences of form factors shows that the wave function of the 6Li nucleus in the 6Li (3.56 MeV) state has increased spatial dimension compared to the 6Lig.s. state.

[1] Y. Suzuki, Nucl. Phys. A 528, 395 (1991).

[2] K. Arai et al., Phys. Rev. C 51, 2488 (1995).

[3] D. M. Rodkin, Yu. M. Tchuvil’sky, JETP Letters, 118 (3), 153 (2023).

[4] A.S. Demyanova et al., “Possible existence of neutron-proton halo in 6Li” KnE Energy & Physics, 1, DOI 10.18502/ken.v3i1.1715 (2018).

[5] I.N. Izosimov, Phys. At. Nucl. 80, 867 (2017).

In the A=8 multiplet, a halo was first discovered in $^8$B in [1] based on the increased quadrupole moment. It was shown that the halo structure is core $^7$Be and has a valence proton. It should be noted that the halo was discovered despite the presence of both the Coulomb and centrifugal barriers. In [2], using total cross sections, the presence of a proton halo in $^8$B was confirmed, and the root-mean-square radius R$_{rms}$ = 2.58 fm and the halo radius R$_h$ = 4.24 fm were determined. However, the latest research indicates that $^8$B looks like a normal heavy ion [3]. All experiments confirm a narrow width of the longitudinal momentum distribution of the core, and an obvious tail structure in the density distribution.

This implies that mirror nuclei $^8$Li will be an interesting candidate for exploring the formation of the halo structure. Many calculations have been made to investigate its structure, such as ab initio calculations, the cluster model, the shell model, the Hartree-Fock method, and the relativistic mean field. In fact, there is still a large ambiguity to explain the structure of $^8$Li theoretically due to the lack of experimental constraints. Although some of these methods could reproduce the radius or the quadrupole moment for $^8$Li well, none of them could well describe both 8Li and 8B simultaneously.

Meanwhile, several groups have tried to determine its structure directly by deducing its matter radius or density distribution through the measurement of cross sections. In [4] using total cross sections, it is stated that there is no halo in $^8$Li. In [5] $^8$Li was found to have a skin-like structure by comparing with the Li isotope and its mirror $^8$B. However, the structure of the $^8$Li nucleus still cannot be clearly concluded, especially for excited states.

We applied Modified diffraction model (MDM) to existing literature data on d+$^8$Li and $^8$Li+$^{12}$C scattering and obtained radii of low-lying excited states of $^8$Li, practically similar as for g.s.

Nowadays the major problem in cosmology is in the choice of the valid gravity theory for interpretation of the observational data. Usually in cosmology it is used the Einstein general theory of relativity and the corresponding Friedman-Robertson-Walker equations in the strong field limit (when gravitational potential is of the order of square of the light velocity). Meanwhile, the general theory of relativity is verified and confirmed only in the weak field limit in the nearest cosmological environments. Observations of black hole images (silhouettes) opens a unique possibility for the verification (or falsification) of modified gravity theories in the strong field limit when gravitation dominates over astrophysical or cosmological factors. This is especially crucial for physical interpretation of astrophysical and cosmological observations of the far regions of the Universe and for understanding the physical origin of enigmatic dark matter and dark energy. The first visual images of supermassive black holes M87 and SgrA have been observed recently by the Event Horizon Telescope. These images demonstrate a qualitative agreement with the general theory of relativity. In the nearest future it would be possible to quantitatively scrutinize the known modified gravity theories after construction of the Space Millimetron Observatory with nano-arcsecond angular resolution.

The founders of quantum geometrodynamics assumed that spacetime may have nontrivial topology: John Wheeler suggested the idea of spacetime foam; Stephen Hawking wrote that one would expect that quantum gravity would allow all possible topologies of spacetime. Later, A. D. Sakharov put forward yet more exotic hypothesis that metric signature may change. Then the question arises, do we really need to take into account all these hypothetical phenomena when quantizing gravity? Since observational data witnesses for an open flat universe, it is possible, in principle, to construct a theory of perturbations of gravitational and matter fields. However, it would not be a full quantum theory of gravity. I shall argue that the assumption about nontrivial spacetime topology, etc. leads to a new description of the Universe in which periods of unitary evolution give place to non-unitary changes of the Universe state. It gives a hope that it may shed light on an origin of irreversibility.

We study the stability of classical solutions in Horndeski theory, which is the most general scalar-tensor theory of gravity with an additional scalar field and second-order motion equations, which in turn provides absence of Ostrogradski ghosts. In this work, we address a general dynamical spherically symmetric background. We derive the set of stability conditions in the cubic subclass of Horndeski theory and formulate the no-go theorem for this subclass.

For full Horndeski theory and beyond Horndeski theory we formulate a set of linear stability conditions for high energy odd parity perturbation modes above an arbitrary solution. In this general setting we derive speeds of propagation in both radial and angular directions for gravity waves and compare them with the speed of light in the case of minimally coupled photon. In particular, we find that the class of beyond Horndeski theories, which satisfy the equality of gravity waves’ speed to the speed of light over a cosmological background, feature gravity waves propagating at luminal speeds above a time-dependent inhomogeneous background as well. [arXiv:2408.01480]

We revisit the models recently derived from a Kaluza-Klein compactification of higher dimensional Horndeski theory, where the resulting electromagnetic sector features non-trivial couplings to Horndeski scalar. In this work we prove that both gravitational wave and its electromagnetic counterpart propagate at the same, although non-unit, speed above an arbitrarily time-dependent, spherically symmetric background within the theories in question. Hence, we support the statement that several subclasses of Horndeski theories are not necessarily ruled out after the GW170817 event provided the photon-Galileon couplings are allowed. We also formulate the set stability conditions based on odd parity perturbations for an arbitraty solution within the discussed theoretical setting. [arXiv:2408.06329]

The $4d$ gravitational model with real scalar field $\varphi$, Einstein and Gauss-Bonnet terms
is considered. The action contains potential term $U(\varphi)$ and Gauss-Bonnet coupling function $f(\varphi)$.
For a special (static) spherically symmetric metric
$ds^2 = \left(A(u)\right)^{-1}du^2 - A(u)dt^2 + u^2 d\Omega^2$
with $A(u) > 0$ ($u > 0$ is a radial coordinate)
we verify and correct the so-called reconstruction procedure suggested by
Nojiri and Nashed. This procedure presents certain implicit relations
for $U(\varphi)$, $f(\varphi)$ which lead to exact solutions
to the equations of motion for a given metric governed by $A(u)$.
Here we apply the procedure to (external) Schwarzschild metric with gravitational radius $2 \mu $ and $u > 2 \mu$. Using ``no-ghost'' restriction (i.e. reality of $\varphi(u)$) we find two family of $(U(\varphi), f(\varphi))$. The first one gives us the Schwarzschild metric defined for $u > 3 \mu$ and the second one describes the Schwarzschild metric defined for $ 2 \mu < u < 3 \mu$ ($3 \mu$ is the radius of photonic sphere). In both cases potential $U(\varphi)$ is negative.

Cosmological models based on scalar-torsion gravity with non-minimal coupling between the scalar field and torsion are considered. These models were obtained as a consequence of the generalized exact solutions of cosmological dynamic equations for an arbitrary Hubble parameter and an arbitrary scalar field evolution.

An inflation models classification according to the expansion order of the tensor-to-scalar ratio dependence on spectral index of the scalar perturbations $r=r(1-n_{S})$ was also proposed. On the basis of this classification, the method for constructing inflationary models based on scalar-torsion gravity verified by observational constraints was considered, implying a linear dependence $r\sim(1-n_{S})$ for arbitrary model's parameters.
For the gravity theory under consideration the type of scalar field potential or other background parameters doesn't affect the possibility of verifying the inflationary models.

Also, proposed inflationary models can predict different types of tensor perturbation spectrum (red, blue or flat) depending on the tensor-to-scalar ratio value and how close the early universe cosmological dynamics is to the purely exponential (de Sitter) expansion regime.
The proposed type of the scalar-torsion gravity implying the wide class of verified cosmological models with arbitrary parameters is of interest for the further deviations research in the relict gravitational waves spectrum and in the compact astrophysical objects evolution from teleparallel equivalent of general relativity or from the other modified gravity theories.

This work considers two classes of cosmological models based on scalar-tensor theories of gravity. The models are obtained using certain functional relationships between the dynamics of the expansion of the Universe and the type of scalar-tensor theories of gravity. The consistency of the models with observational constraints according to Planck-2018 data is considered.

We propose new slow-roll approximations for inflationary models with the Gauss-Bonnet term. We find more accurate expressions of the standard slow-roll parameters as functions of the scalar field. To check the accuracy of approximations considered we construct inflationary models with quadratic and quartic monomial potentials and the Gauss-Bonnet term. Numerical analysis of these models indicates that the proposed inflationary scenarios do not contradict to the observation data. New slow-roll approximations show that the constructed inflationary models are in agreement with the observation data, whereas one does not get allowed observational parameters at the same values of parameters of the constructed models in the standard slow-roll approximation.

The analysis of the latest most accurate experimental data on neutron decay for the possibility of the existence of a right vector boson $W_R$ was carried out. As a result of the analysis, it was found that there is an indication of the existence of a right vector boson $W_R$ with a mass of $M_{W_R }= 304_{-22}^{+28}$ GeV and a mixing angle with $W_L: \zeta = -0.038\pm{0.014}$. This result should be considered, on the one hand, as a challenge to experimental physics at colliders, where the upper limit on the mass of the right vector boson $W_R$ is significantly higher, and on the other hand, it indicates the need for even more accurate measurements of neutron decay and its theoretical analysis. Possible consequences are considered, assuming that the result can be confirmed. First, an extension of the SM by introducing right vector bosons $W_R^±$, $Z_R$ and right neutrinos would be required. Second, right neutrinos can be considered as candidates for dark matter.

The SHiP (Search for Hidden Particles) experiment is a new fixed-target experiment to be installed at the CERN SPS ring with a 400 GeV proton beam energy. The primary goal of the experiment is to detect signals from the Hidden Sector particles, introduced to describe dark matter, baryon asymmetry, and small neutrino masses. To suppress background, an iron magnetized hadron absorber and a muon shield are utilized, along with several veto systems, aiming to reduce the experiment's overall background to zero over 5 years of operation.

SND (Scattering and Neutrino Detector) is the SHiP detector project designed to detect neutrinos of all flavors and direct signals from Light Dark Matter (LDM) interactions. An updated design for SND@SHiP includes a high-granularity hadron calorimeter achieved using scintillating fibers (SciFi) and scintillator layers (Scint).

A key focus of this work is the classification of tau-neutrino events in the SND. This includes distinguishing tau-neutrino interactions via charged current (CC) deep inelastic scattering (DIS) followed by tau lepton decay in both leptonic and hadronic channels, from the background of muon-neutrino interactions via CC and neutral current (NC) DIS. Specifically, the classification is focused on:

• Signal from inelastic interaction of tau-neutrinos via charged current on nuclei followed by tau lepton decay in the leptonic channel (CC DIS $ \nu_{\tau} N \rightarrow \tau + X \rightarrow \mu \nu_{\tau} \nu_{\mu}+ X $) against the background of signal from inelastic interaction of muon neutrinos via charged current on nuclei (CC DIS $ \nu_{\mu} N \rightarrow \mu + X $).
• Signal from inelastic interaction of tau-neutrinos via charged current on nuclei followed by tau lepton decay in the hadronic channel (CC DIS $ \nu_{\tau} N \rightarrow \tau + X \rightarrow hadrons + X $) against the background of signal from inelastic interaction of muon neutrinos via neutral current on nuclei (NC DIS $ \nu_{\mu} N \rightarrow \nu_{\mu} + X $ ).

The search for tau-neutrino signal was performed using reconstructed kinematics of secondary particles and detector response. Inelastic neutrino interaction events from the SHiP experiment spectrum on nuclei were simulated using the GENIE package, and secondary particles were passed through the detector using the GEANT4 package. Simulations show that the average error in muon momentum determination is about 12%, while vertex reconstruction accuracy is $\sim$1.5 cm. The energy resolution for pions ranges from $\sim50\%/\sqrt{E}$ for energies between 1 and 100 GeV. A classifier was developed using machine learning methods trained on both kinematic and detector response variables, capable of accurately classifying event types.

Search for Dark Matter (DM) particles is one of the most interesting problem in modern physics. Light dark matter particles may be produced in decays of the Higgs boson that would appear invisible to the detector.
"Higgs portal" models predict decay of Standard Model Higgs boson into pair of WIMP particles, which are strong candidates for DM. The production of Higgs Boson in vector boson fusion process (VBF+MET), followed by Higgs decay into DM particles is the most promising channel for the search due to high signal sensitivity. This talk presents latest results for VBF+MET and statistical combination of Higgs invisible searches obtained at ATLAS Large Hadron Collider experiment using data collected for Run II ($\sqrt{s}$ = 13 TeV).

Dark SHINE is a fixed-target experiment initiative at SHINE (Shanghai high repetition rate XFEL and extreme light facility, being the 1st hard X-ray FEL in China) under construction targeting completion in 2026. Dark SHINE aims to search for the new mediator, Dark Photon, bridging the Dark sector and the ordinary matter. In this work and presentation, we present the idea of this new project and 1st prospective study in search for Dark Photon decaying into light dark matter. It also provides the opportunity to incorporate broader scope of BSM search ideas utilizing the fixed-target experiment of this type.

Refererence:

Sci. China-Phys. Mech. Astron., 66(1): 211062 (2023), DOI:10.1007/s11433-022-1983-8

arXiv:2311.01780

arXiv:2310.13926

arXiv:2401.15477

DOI:10.5281/zenodo.8373963

The goal of the Troitsk nu-mass experiment is a search for sterile neutrinos in the tritium beta decay. The decay electrons are produced in the windowless gaseous tritium source, WGTS. The magnetic field in the source is formed by a set of solenoids. Electrons produced at large pitch angles to the magnet axis are trapped. Electrons at small angles can leave the WGTS for the spectrometer or in the opposite direction, for the rear wall. The spot of electrons escaping from the WGTS to the rear wall increases in diameter due to the fringe field. These electrons may scatter on the vacuum pipe and at some combination of scattered angle and final energy, may return to the WGTS and reach the spectrometer and detector. This contamination modifies the original tritium spectrum. We calculate the scattered electron distribution in GEANT4 framework and then apply energy and angular cuts to select the electrons that can reach the detector. The relative contribution of such electrons is 4-5 orders of magnitude less at the edge of the original spectrum at 17-18.5 keV, but reaches 2% at 11 keV. The experimental spectrum fits well with a correction for this contribution. The study of the rear wall contribution, its magnetic field and material configuration is critical for the TRISTAN project, the follower of the KATRIN experiment.

Physicists carry out experiments at the modern accelerators with constantly increasing energy to find out new phenomena and approaches to understanding of internal hadron structure and also answer many questions emerged before them. These experiments agree well on the modern theory of strong interactions, quantum chromodynamics, but there are some results in cosmological observations that can not be explained in this theory and require new approaches and experiments. In that way the increasing of measurement precision and rare event registration, building of other theoretical models and just to name a few can help. Also we think that more detailed analysis of the known interactions can make more clear structure of matter.
Multiparticle production is one of such studies in high energy physics.
We offer the single view to describe annihilation processes of leptons and hadrons. It is based on both QCD quark-gluon jets and phenomenological description of hadronization.

Zakharov et al. (2005a) predicted an opportunity to reconstruct a shadow in Sgr A$^*$ with ground based or space-ground interferometer acting in mm or sub-mm band (the Millimetron was mentioned for such needs). The prediction was realized in May 2022 since the Event Horizon Telescope (EHT) Collaboration presented results of a shadow reconstruction for our Galactic Center (earlier the shadow around the supermassive black hole in M87 was reconstructed in 2019). These reconstructions were based on EHT observations done in 2017. For Reissner--Nordstr$\ddot{\text{o}}\text{m}$ metric Zakharov et al. (2005b) derived analytical expressions for shadow size as a function of charge and later these results were generalized for a tidal charge case (Zakharov, 2014). We discuss opportunities to evaluate parameters of alternative theories of gravity with shadow size estimates done by the EHT Collaboration, in particular, a tidal charge could be estimated from these observations (Zakharov, 2022). We also discuss opportunities to use Millimetron facilities for shadow reconstructions in M87$^*$ and Sgr A$^*$. In our recent studies (Zakharov, 2024) we discuss shadow formations for cases where naked singularities or wormholes substitute black holes in galactic centers.

References

Zakharov A. F., Nucita A. A., De Paolis F., Ingrosso G. (2005a) New Astron., 10, 479

Zakharov A. F., De Paolis F., Ingrosso G., Nucita A. A. (2005b) A & A 442, 795

Zakharov A. F. (2014) Phys. Rev. D 90, 062007

Zakharov A. F. (2022) Universe 8(3), 141

Zakharov A.F. (2024, in press)

High energy neutrino astronomy has seen significant progress in the past few years. This includes the detection of neutrino flux from the Galactic plane, as well as strong evidence for neutrino emission from the active galaxy NGC 1068, both reported by IceCube. New results start coming from the two km3-scale neutrino telescopes under construction in the Northern hemisphere: KM3NeT in the Mediterranean sea and Baikal-GVD in Lake Baikal. After briefly reviewing the status of the field, we present the current status of the Baikal-GVD neutrino telescope and its recent results, including observations of atmospheric and astrophysical neutrinos.

The report summarize results of a series of papers on modelling the nuclear-physical evolution of the outer layers (crust) of neutron stars in low mass X-ray binaries. In these systems, material is transferred from the companion star to the neutron star, a process known as 'accretion' in astrophysical literature. As a result, the original crust is replaced by accreted material.

We demonstrate that the presence of free neutrons (unbound in atomic nuclei) in the inner crust plays a crucial role in the nuclear physical process of forming the accreted crust. Neutrons redistribute rapidly between the layers of the inner crust due to superfluidity and diffusion (with diffusion being important near the boundary between the outer and inner crust, where neutrons are not superfluid). This effect was not considered in previous models developed over approximately 40 years, leading to a radical change in the nuclear reactions chains and the composition of the crust. Consequently, several previously accepted statements are shown to be incorrect. For instance, it was previously believed that the main reactions in the inner crust were electron capture and neutron emission, and the transition to the inner crust was associated with reaching the neutron drip line. In our work, we demonstrate that reverse reactions occur in the inner crust (neutron capture and electron emission), and the boundary between the inner and outer crusts is determined by the redistribution of free neutrons in the crust and the star's core, maintaining diffusion-hydrostatic equilibrium.

We propose and apply a general, convenient formula based on the energy conservation law for calculating the heating efficiency of the crust, which is shown to be several times lower than previously estimated. These findings are then applied to interpret observations of accreting neutron stars.

The work was supported by the Russian Science Foundation, grant 22-12-00048.

A wide range of extreme states of the nuclear matter that cannot be studied in terrestrial conditions is realized in neutron stars, making them a source of information on the properties of baryonic interactions and nuclear matter under conditions different from those in the most stable nuclei. Under such conditions, additional sensitivity to certain properties of baryonic interactions may arise. At densities several times higher than the normal nuclear density, hyperons may appear in the neutron star matter.

In this paper, we study the dependence of the observables of neutron stars, such as the maximum mass, the corresponding minimum radius, the tidal deformability coefficient for stars with a mass of 1.4M$\odot$ and their radius on the properties of hyperon-nucleon and nucleon-nucleon interactions.

In particular, a strong interplay was established between the parameters of neutron stars and the density at which hyperons appear, as well as the contracting power of YN interactions.

This work was supported by the Russian Science Foundation under Grant No 24-22-00077

The discovery of lanthanides traces in the kilonova spectra after recording a gamma-ray burst and gravitational waves [1] confirmed theoretical scenarios for the development of the r-process [2], associated with the neutron stars merger at the end of a close binary system evolution. After successful r-process simulation that occurs as a result of the neutron stars merger and observing these events, it became clear that this scenario is crucial for the heaviest nuclei formation. However, the neutron stars evolution in close binary systems strongly depends on their masses. With a large neutron stars masses difference, a stripping scenario is implemented instead of merging [3], which, in particular, has different heavy elements nucleosynthesis path [4,5].

In this work the nucleosynthesis in the low-mass neutron star crust, which loses mass due to accretion onto a larger companion and explodes upon reaching a hydrodynamically unstable configuration [3] is considered.

It was shown that in the stripping scenario the exploded residue substance expands and, while its density is high, new elements nucleosynthesis occurs. In the inner crust it originates mainly due to the r-process. Nucleosynthesis in the outer crust occurs mainly due to explosive nucleosynthesis following sharp increase in temperature caused by a shock wave, and forms significant number of light nuclei. A simple model of subnuclear dense matter decompression is proposed. The amount of heavy elements formed in a neutron star crust is M ~ 0.04Mʘ, which is at least an order of magnitude greater than the yield of heavy elements in the close masses neutron stars mergering scenario [6].

The work was carried out within the state assignment framework of the National Research Center «Kurchatov Institute».

1. N. R. Tanvir, A. J. Levan, C. González-Fernández, et al. // AJ. 2017. V. 848. P. L27.
2. J. Cowan, et al. // Rev. Mod. Phys. 2021. V. 93. id. 15002.
3. S. I. Blinnikov, D. K. Nadyozhin, N. I. Kramarev, A. V. Yudin // Astronomy Reports. 2021. V. 65. P. 385.
4. I.V. Panov, A.V. Yudin // Astronomy Letters. 2020. V. 46 P. 518.
5. A. Yudin, N. Kramarev, I. Panov, A. Ignatovskiy // Particles. 2023. V. 6. P. 784.
6. S. Rosswog, et al. // Astron. Astrophys. 1999. V. 341. P. 499.

The process of dust heating by photons from primordial black hole (PBH) in a molecular cloud with masses $M = 10^{16} - 10^{20}$ g has been considered. Under the assumption that dust particles are uniformly distributed in a spherically symmetric cloud and have sizes $a = 0.01, 0.02, 0.05$, and $0.1$ $\mu$m, the dust temperature as a function of the distance to the PBH was calculated. From the plots obtained, it follows that directly near the PBH the dust particles are heated to a temperature $T \leq 10^2$ K, and with increasing distance the temperature drops sharply. Thus, PBH can heat only a spherical layer of the molecular cloud whose radius $r$ does not exceed $10^3$ cm. In addition, the emission spectra of dust particles heated by PBH were constructed and it was shown how the spectra depend on the dust number density in the molecular cloud and on the particle size. The sensitivity plots of the planned Millimetron space observatory in the interferometer mode were superimposed on the obtained spectra and it was shown that in the presence of PBH in the cloud, it can be registered if the dust number density in the cloud is between $n_d = 10^{-4}$ cm$^{-3}$ and $n_d = 10^{-1}$ cm$^{-3}$ (with the size of individual dust particles in the cloud varying from $0.1$ to $0.01$ $\mu$m, respectively).

The possibility of an analytical approximation of nonequilibrium neutrino radiation under core-collapse supernova conditions is considered. Analysis is based on results of a one-dimensional simulation of neutrino propagation, performed self-consistently with hydrodynamics in Prometheus-Vertex code. In minimal model, an analytical approximation depends on four parameters at each point of the supernova. As the analysis shown, in the outer part of the supernova the dependence of these parameters on the radial coordinate can be expressed through the radius of the protoneutron star, luminosity, spectrum width and the average energy of the neutrinos leaving the supernova. Note that the values of last two parameters are practically same in various simulations of the supernova explosion. Thus, in the outer part the neutrino radiation is determined only by two global parameters of the explosion: the protoneutron star radius and the neutrino luminosity.

The work is supported by the Russian Science Foundation (Grant No.
24-22-00417, https://rscf.ru/project/24-22-00417/)

Baikal-GVD is a neutrino telescope with an effective volume of approximately 1 km³, located in Lake Baikal. This experiment leverages a neural network-based approach to address multiple challenges in data analysis:

1. Suppression of noise hits of the optical modules (OMs) caused by the natural luminescence of the medium, while preserving signal hits generated by Cherenkov radiation;
2. selection of events caused by neutrinos against the dominant background of events caused by extensive air showers;
3. Reconstruction of the neutrino's arrival direction;
4. Reconstruction of neutrino energy.

Monte Carlo simulations demonstrate that the developed neural networks achieve performance metrics comparable to traditional methods. Futhermore, for task 1, the neural network surpasses standard techniques (achieving 99.5% "precision" metric versus 95%). For task 2, a novel method developed that estimates the total number of neutrino-induced events in a dataset and the associated error. In task 4, a neural network model is developed to predict the energy of neutrino events along with an estimate of the prediction error, corresponding to one standard deviation.

Despite the overwhelming indirect evidence, the nature of dark matter is still a mystery. This talk will overview the experimental efforts to detect Dark Matter directly, highlighting the latest findings from relevant experiments. Additionally, we will explore emerging technologies aimed at detecting very light Dark Matter candidates. This talk will also discuss the neutrino floor and its implications for future dark matter searches.

Studying of transient phenomena reveals some of the most dynamic and explosive objects in the Universe. These transients are crucial for gaining insight into the behavior and evolution of the cosmos. They also help us understand the physics behind non-transient sources, such as how supernovae provide clues about stellar evolution. Regardless of how transients are used to explore different aspects of the universe, they will remain a key focus in astronomy, especially as new telescopes and surveys are developed to observe our ever-changing cosmos.

In current work, we studied transient events such as Fast Radio Bursts (FRBs) and Gravitational Waves (GWs) using the Borexino detector signals $\pm5000$ s within time windows around the prompt event. We searched for temporal correlations for 42 FRBs with ΦFRBi > 40 Jy·ms, and also investigated temporal correlations for 74 GWs, including those presumably originating from black hole mergers and neutron star mergers. In both searches no statistically significant excess of events was observed. As a result, new strict upper limits have been set on $\nu_x$ fluences in the 0.5–15 MeV energy range for temporal correlations with FRBs, and new limits on $\nu_x$ fluences in the 0.5–50 MeV range for GW events.

Abstract

The results obtained in two series of measurements within 2023-2024 years with a multi-cathode counter with an iron cathode are presented. We observe some excess in count rates at certain periods in sidereal time. No similar effect has been observed in terrestrial time. This can be interpreted that probably this effect is of galactic origin and being this can be associated with dark photons. The future steps are discussed to increase the reliability of the results and to clarify important details.

Abstract.
Quark-less baryonium diagram appeared in the old paper on baryonium physics (L. Montanet, G.C. Rossi, G.Veneziano, 1980). If two gluon lines in this diagram are cut, we have tetraquark with two quarks and two anti-quarks. This idea can be expanded to multi baryon-antibaryon states of Baryonium Dark Matter (BDM), see (Piskounova, 2023). Baryonium Dark Matter consists of the net of baryon and antibaryon String Junctions (SJ) completely connected via gluons on the surface of torus. BDM states have no quarks and zero baryon charge because of equal numbers SJs and anti-SJs. The progression of BDM mass was assumed exponential that is natural for QCD physics, see (O. Piskounova, 2016). The low mass baryonium states are studied in order to show how they correspond to the BDM mass sequence. Previously-observed heavy baryonium states (1835 MeV, 1851 MeV and 1859 MeV are very close to the third order mass in BDM progression, $1855\pm15$ MeV, see (Piskounova , 2019). Since BDMs particles are quark-less and rather compressed, they have hidden mass and can be deconstructed into charmed baryonium resonance, or into charmed tetraquarks, pentaquarks, hexaquarks etc. Each product may be accompanied at the deconstruction of BDM with dozens of pions and photons. In such a way, the states of BDM have to be considered as the progenitors of particles in hadron generations. Next state of BDM is expected of mass near the beauty family of hadrons, $5042\pm40$ MeV. The important advantages of Baryonium Dark Matter for astrophysics of Universe have been discussed.

The emergence of relativistic quantum gravitational effects is well anticipated when the Planck density ($m_p/\ell_p^3$, where $m_p$ is the Planck mass and $\ell_p$ is the Planck length), regardless of whether the prediction of an infinite-density singularity is viewed as a flaw in general relativity. Over the past century, the orthogonality between quantum mechanics and general relativity has been a persistent issue, prompting the dedicated efforts of brilliant scholars. Our focus is on a quantum geometric approach that expands the four-dimensional Riemann geometry (spacetime) to incorporate quantum-mechanical principles. This approach enables a comprehensive exploration of the fundamental nature of the Universe, offering a more profound understanding of the underlying relativity and quantum principles governing its structure and evolution. The quantum geometric approach facilitates the derivation of the fundamental tensor, upon which quantum-mechanically induced revisions are imposed. This, in turn, allows for the construction of the general theory of relativity and the verification of various black hole metrics, while also enabling the examination of initial and space singularities through timelike geodesic congruence.

Massive primordial black holes may have formed in the early universe, accounting for a small fraction of dark matter. Most of dark matter, however, may be composed of elementary particles or black holes with smaller masses. These objects could form dense spikes around the large black holes during the radiation-dominated phase of the universe's evolution. Dark matter particles can annihilate in the spikes. In this study, we discuss the structure and properties of the spikes, considering their transformation due to annihilation. In the hybrid scenario involving black holes of various masses, small black holes can scatter and merge in the central regions around larger black holes.

We consider the formation and dynamics of primordial black holes (PBHs) binaries in both the early and late Universe, taking into account clustering effects. The evolution of the PBH merger rate with redshift is obtained and shown to depend on the clustering efficiency. The observation of gravitational waves by the LIGO-Virgo-KAGRA collaboration imposes the constraint that PBHs constitute no more than 10% of the dark matter.

This work is devoted to the analysis of the influence of tidal effects on the shape of the gravitational signal from the fusion of neutron stars. The main part of the work is divided into theoretical information, analytical and numerical models, and practical implementation.

The theoretical section includes a description of the basic model for black holes and neutron stars, as well as the methods used to add tidal effects. The basic model is based on the post-Newtonian approach, which allows us to take into account the effects of interaction of compact objects without solving the Einstein equations. Within the framework of this model, a differential equation arises describing the evolution of the post-Newtonian parameter, and it is further solved in two different ways.

The practical part includes calculating the parameters of the model and solving the differential equation using maxima code.

The discussion section of the results presents a comparison of numerical and analytical solutions. It turns out that the analytical solution allows you to look a little further in time and evaluate the behavior of the system at closer distances.

The conclusion summarizes the work performed, indicating the fulfillment of the tasks set, such as the analysis of modern models, calculation of coefficients for differential equations, and comparison of the results obtained by different methods. In the future, it is planned to continue work on calculating the shape of the gravitational wave signal from merging black holes and adding tidal effects to the model for calculating the shape of gravitational waves.

The influence of non-minimal coupling between the scalar field and the Gauss-Bonnet term on the background parameters of cosmological models and the parameters of cosmological perturbations is considered by comparison with the case of the Einstein gravity. The possibility of parametrization of this influence is shown.
A procedure for reconstructing solutions of the cosmological dynamic equations obtained within the framework of General Relativity for the case of the Einstein-Gauss-Bonnet gravity is presented.
As an example, some models of cosmological inflation are considered. It is shown that these cosmological models can be verified by observational constraints on the parameters of cosmological perturbations by taking into account the influence of the Gauss-Bonnet term.
Also, proposed cosmological models satisfy modern observational constraints on the propagation speed of the gravitational waves.

The specificity of the spectrum of relic gravitational waves for inflationary models based on Einstein-Gauss-Bonnet gravity in comparison with the case of General Relativity is considered.
The effect of increasing energy density of the high-frequency relic gravitational waves in the proposed inflationary models is analyzed.
The possibility of registering relic gravitational waves predicted in these inflationary models is considered as well.
To assess the possibility of detection of relic gravitational waves, the application of classical and modified Herzenstein effects and the high-frequency gravitational-optical resonance in multi-beam interferometers are analysed.

Microlensing experiments searching for MACHOs (massive astrophysical compact halo object, MACHO) have limited the possibility of the existence of dark matter in the form of MACHOs. These constraints on the fraction of dark matter are made for single MACHOs. The microlensing light curve for single MACHOs agrees well with the standard microlensing model. However, the mutual influence of clustered MACHOs can significantly change the light curves and therefore change the constraints on the MACHO fraction.

We have simulated microlensing events for models of the class of clustered primordial black holes (PBH). The analysis of microlensing events for these cluster models showed that the fraction of MACHO mass that is not detected as single ones can reach up to 40%. Therefore, observations of experiments such as MCHO, EROS, OGLE, POINT-AGAPE, HSC can impose tighter constraints on the fraction of MACHOs. Although the models of PBH clusters that we consider reduce the limitations due to clustering, it is not possible to completely remove the limitations on MACHO.

We investigated the evolution of the mass spectrum of primordial black holes (PBHs) in the expanding Universe under the action of Bondi-Hoyle-Lyttleton accretion and Hawking radiation. The initial mass spectrum of primordial black holes was assumed to be flat (independent of mass). It was shown that accretion of matter surrounding a black hole does not significantly affect the growth of the mass of black holes. Using modeling, it was found that by the end of the radiation-dominated era, all primordial black holes with masses up to $M=2\times10^{9}$ g had evaporated. We also confirmed the critical mass value for primordial black holes, at which they evaporate in our time. It is $M_{cr}=2\times10^{14}$ g.

We discuss a class of solutions of multidimensional gravity which are formally related to black-hole solutions but can observationally look like stars whose surface reflects back particles or signals getting there. Some particular examples of such solutions are presented and studied.

Nuclotron complex gives the unique opportunity to study spin effects using polarized deuteron and proton beams from new polarized ion source. Recent results on the spin effects in deuteron-proton and proton-proton elastic scattering are discussed. The data on the deuteron analyzing powers Ay, Ayy and Axx obtained at large transverse momenta in the energy range 400-1800 MeV demonstrate the sensitivity to the short-range spin structure of the isoscalar nucleon-nucleon correlations. The data on the beam analyzing power in proton-proton quasi-elastic scattering can be used to improve the phase-shift analysis in the Nuclotron energy range of Nuclotron
The perspectives of further progress in physics program as well as in the development of the beam polarimetry and proton spin manipulation techniques are disscussed.

The Beam-Beam Counters (BBC) are components of the Spin Physics Detector at the NICA collider. They are designed to perform local polarimetry of the colliding polarized proton and deuteron beams and luminosity control in the beam interaction region. Here, the MC simulation of the BBC operation for proton-proton collisions is presented. The simulations are performed using the SpdRoot framework and the center-of-mass energy of 27 GeV. The results presented include the estimation of the magnetic field influence on the inclusive charged particle production asymmetries and the BBC. The selection of the pp-elastic scattering events in the BBC is also discussed.

It is proposed to do a search for the light dibaryons in the experiment with the future SPD detector on the NICA collider at JINR . It is proposed that the reaction d + d → d + X should be measured at the collider momentum 2.6 GeV /c with the registration of the deuteron and proton in a final state.The achievable accuracies are estimated in different configurations of the detector with allowance to its gradual modifications up to completion. The counting rate of the reaction is estimated at ≈ 2 s−1 and the accuracy of mass measurement in the first version of the detector at ≈ 4.7 MeV

Direct photons produced in quark-gluon and quark-antiquark interactions are planned to be studied in detail in the upcoming SPD experiment at the NICA collider. Direct photons serve as important probes for understanding the dynamics of interactions in high-energy nuclear collisions.

An important aspect for understanding the production of direct photons are parton distribution functions (PDFs), which determine the probability of detecting quarks and gluons with given characteristics inside nucleons. PDFs can differ significantly for free and internuclear nucleons. The differences between these functions can be investigated through the invariant spectra and nuclear modification factors of direct photons in deuteron-deuteron collisions.

In this paper, we present calculations of the invariant spectra and nuclear modification factors of direct photons as a function of transverse momentum in the rapidity region $|y|<3$ at energies $\sqrt{s_{NN}}=13.5$ GeV and $\sqrt{s_{NN}}=27$ GeV.

We acknowledge support from Russian Ministry of Education and Science, state assignment for fundamental research (code FSEG-2024-0033).

A study of direct photon production in longitudinally polarized proton-proton collisions presents a valuable opportunity to investigate the contribution of gluons to the total proton spin. This contribution is described in terms of a gluon helical distribution function, $\Delta g(x)$. An investigation of this function forms part of the experimental program scheduled for the SPD experiment. The extraction of $\Delta g(x)$ is achieved through the measurement of double longitudinal spin asymmetry (DLSA) in direct photon production.

The study of direct photons presents certain challenges. Due to their relative rarity, it is difficult to distinguish direct photons from those produced by other sources. Consequently, it is challenging to obtain a substantial sample size. One potential solution is the application of generative machine learning models, such as generative adversarial networks (GANs). The model can be trained to predict the outcome of longitudinally polarized proton-proton collisions without modeling the entire experiment in detail, but only the relevant process.

As the SPD experiment is still under construction, a PYTHIA8 Monte Carlo generator with polarized NNPDFpol11 was selected for testing the potential of using GAN to predict the production of direct photons in longitudinally polarized proton-proton collisions.

The present report is devoted to an investigation of the capabilities of GAN in predicting the outcomes of direct photon production in both polarized and unpolarized proton-proton collisions at a center-of-mass energy of $\sqrt{s} = 27$ GeV.

We acknowledge support from Russian Ministry of Education and Science. State assignment for fundamental research (code FSEG-2024-0033)

The possibility of measuring spin correlation parameter in elastic proton-proton and antiproton-proton scattering in the SPASCHARM experiment at U-70 accelerator complex at Protvino is discussed. The measurements will be carried out using polarized beams and a polarized target of the experiment. A realistic simulation of the experiment was carried out and an evaluation of the accuracy of ANN measurements of elastic pp and p p scattering at an energy of 16 GeV and the time required to measure this observable in both reactions was made.

The first results on the polarization of inclusively produced $\Lambda$-hyperons in the $K^{-}$- and $\pi^{-}$-beams and $\bar{\Lambda}$-hyperons in the $\pi^{-}$-beam with a momentum of 26.5 GeV/$c$ were obtained at the SPASCHARM facility at the U-70 accelerator complex in Protvino. For the data on the $K^{-}$-meson beam, a noticeable positive polarization is observed in the region of large values of the Feynman variable $x_F$ and the transverse momentum $p_T$, which was measured for the first time on nuclei. The polarization of $\Lambda$- and $\bar{\Lambda}$-hyperons in the $\pi^{-}$-beam does not exceed several percent in most of the studied kinematic region, with the exception of the region $p_T>1\ \text{GeV}/c$, where the $\Lambda$ polarization is $23\pm 9$ %.

We report measurements of A-dependence K$^*$-(892) mesons' production in interactions of 26.5 GeV/c K-minus-meson beam and nuclei (C,Al,Cu,W) at SPASCHARM facility at U=70 accelerator complex (NRC "Kurchatov institute" - IHEP, Protvino.
A-dependence of K$^*$-(892) mesons is compared with our results on A-dependence of K0s-mesons and with other experimental measurements.

A review of worldwide experimental study of coherent elastic neutrino-nucleus scattering (CEvNS) is given.

Coherent elastic neutrino nucleus scattering (CEvNS) is a fundamental process within the Standard Model which was observed for the first time in 2017 by the COHERENT experiment on the CsI target at the Spallation Neutron Source (SNS) located in Oak Ridge National Laboratory (USA). This process cross section prevails over the cross sections of all other known neutrino interactions with heavy nuclei within the energy range below 50 MeV due to its dependence on square number of neutrons in the nucleus. The main goal of COHERENT is to measure CEvNS on different targets and to explore related physics opportunities in the neutrino and BSM physics. After the first observation COHERENT has also succeeded in detection of CEvNS on Ar and Ge targets with the latter in 2023.

In this talk we describe the current status of CEvNS study in the COHERENT experiment and talk about efforts to measure inelastic neutrino interactions with Ar, I, O, Pb and Th nuclei. We update our program for neutrino flux measurements at SNS with heavy water detectors. We also present other COHERENT efforts and the search for sterile neutrinos at the Second Target Station of SNS.

RED-100 is a two-phase emission detector with an active volume containing 130 kg of liquid xenon. The detector was exposed to the antineutrino flux of $1.35·10^{13}$ $cm^{−2}s^{−1}$ at a distance of 19 m from the 3.1 GW reactor core of Unit 4 of the Kalinin Nuclear Power Plant (KNPP) . The comparison of count rates measured during the reactor on and off periods shows no statistically significant excess and allows to obtain an upper limit on the cross-section of coherent elastic scattering of antineutrinos on xenon nuclei.

The νGeN experimental setup is deployed at Kalinin Nuclear Power Plant at a distance of 11 m from the center of the Unit 3 core. The experiment aims for observation of coherent elastic scattering of reactor antineutrinos off nuclei (CEvNS) and performs a search of antineutrino magnetic moment (NMM) using a 1.4 kg HPGe detector. Based on the dataset acquired from September 2022 to May 2023 we report a 90% C.L. upper limit on CEvNS cross-section of 5.0/2.0 times larger than the Standard model prediction depending on the assumption of nuclear recoil quenching factor. The 90% C.L. sensitivity of νGeN to NMM evaluated for the same dataset is $5.3\cdot10^{−11} \mu_{B}$, while the increase of exposition to 1100 kg$\cdot$days together with application of a background model allows to reach an upper limit of $2.6\cdot10^{−11} \mu_B$.

on behalf of Daya Bay Collaboration

The Daya Bay experiment was planned to precisely measure the neutrino oscillation parameters $\sin^2 2\theta_{13}$ and $\Delta m^2_{32}$. The antineutrino flux from six nuclear reactors was measured by eight identically designed liquid scintillator detectors at distances from 400 m to 2 km. Four detectors were located in the two near halls and four detectors were located in the far hall. The experiment has accumulated $5.55 \times 10^6$ candidates of the interaction of electron antineutrinos during 10 years of operation. The oscillation parameters are measured with unprecedented precision: $\sin^2 2\theta_{13} = 0.0851 \pm 0.0024$, $\Delta m^2_{32} = (2.466 ± 0.060) \times 10^{−3}$ eV$^2$ assuming the normal mass ordering and $\Delta m^2_{32} = −(2.571 \pm 0.060) × 10^{−3}$ eV$^2$ assuming the inverted mass ordering.

Results of oscillation analysis based on a full dataset will be presented. Additionally, results of the search of sterile neutrinos are included as well.

The DANSS experiment at Kalininskaya NPP is running for already 8 years
since April 2016. More than 8 million inverse beta decay events are already collected. DANSS experimental program includes both search for physics beyond the Standard Model, like sterile neutrinos or large extra dimensions, and applied studies connected to reactor monitoring using electron antineutrino flux. The model independent exclusion area in the sterile neutrino parameter space for 3+1 hypothesis extends till $sin^2(2 \theta) = 0.004$ for $\Delta m^2 = 0.9$ eV$^2$, where sensitivity of the experiment is the best. Our data show presence of the antineutrino with energies above 10 MeV with significance 6.8 $\sigma$. Independent from the NPP standard equipment reactor power measurements during 7+ years demonstrated excellent stability with uncertainty 1.3% for a three days measurement.

Along with ongoing statistics collection DANSS is preparing for an upgrade, which shell significantly improve energy resolution and also increase the fiducial volume. The talk covers recent analysis results
and the upgrade status.

The iDream (industrial Detector of REactor Antineutrino for Monitoring) project is aimed at development of the reactor antineutrino detection technology for an industrial tool creation. The tool can serve for an additional independent control method of a nuclear reactor operation. The 1 ton Gd doped liquid scintillator neutrino detector is placed under the 3rd energy unit of the Kalinin NPP. We are going to present the results of the detector probation during one full fuel cycle, which duration is equal to 510 effective days.

The results of a study of the territory and hidden structure of the buildings of the Spaso-Kamenny Preobrazhenskii Monastery on Kamenny Island in Lake Kubenskoye are presented. The monastery, a cultural heritage site, was founded in 1260. The main purpose of the study was the basements of a bomb exploded in the mid-1930s Preobrazhenskii Cathedral of Monastery. According to the chronicles, there may be a crypt containing the remains of the disgraced primate of the Russian Church, Metropolitan Varlaam, who died in 1533.

Pham K.T.1,2,3*, Nezvanov A.Yu.3, Muzychka A.Yu.3

1. Department of Fundamental and Applied Problems of Microworld Physics, Landau Phystech School of Physics and Research, Moscow Institute of Physics and Technology (National Research University), 141701, Institutskiy Pereulok, 9, Dolgoprudny, Moscow Oblast, Russia

2. Vietnam Atomic Energy Institute, 59 Ly Thuong Kiet, Ha Noi, Viet Nam

3. Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, 141980, Dubna
   *kham.kt@phystech.edu.ru

The calculation of neutron transport is crucial for the development of neutron sources. The accuracy of these calculations depends on the quality of the nuclear data libraries used, which provide information on neutron cross-sections. There are several nuclear data libraries widely used in the world such as the Evaluated Nuclear Data Files (ENDF), the Japanese Evaluated Nuclear Data Library (JENDL), and the TALYS-based Evaluated Nuclear Data Library TENDL, among others.

In our research, we focused on the neutron cross-section library for solid ortho-deuterium (sD2) at 5 K, which is a promising material for the development of the intense sources of very cold (VCN) and ultracold neutrons (UCN). The library was developed in ACE format by the Spallation Physics Group at the European Spallation Source, based on a model developed by J.R. Granada [1]. The model includes details of the lattice density of states, molecular rotations, and internal molecular vibrations, as well as elastic and inelastic processes involving spin-correlation effects.

We have used a Monte Carlo code and this data library for sD2 at 5 K to calculate the cross-sections and found that the results are similar to the measured cross-sections. We also simulated the differential inelastic cross-section of energy transfers when neutrons interact with sD2, comparing our results with those published by A. Frei [2]. Our results showed agreement with Frei's results for sub-thermal neutrons in the sD2 converter material.

In addition, we have also calculated the cross-section of the conversion of VCN with velocities from 50 to 200 m/s using sD2 at 5 K, liquid deuterium at 20 K, water ice at 115 K, and solid mesitylene (C9H12) at 20 K. The wavelength range of incident neutrons for these calculations is from 1 to 20 Å.

In particular, our investigation has shown that the existing libraries are insufficient to provide the necessary data for simulations involving the production and transport of ultracold neutrons (UCNs). Specifically, the data gap is evident in the energy range from $10^{-2}$ to $10^3$ meV. In the next phase of our research, we plan to use J.R. Granada's neutron scattering kernel for sD2 to develop a new cross-section library for Geant4, with a focus on extending its coverage to the energy range relevant for UCNs.

References

[1] Granada, J. R. “Neutron scattering kernel for solid deuterium.” Europhysics Letters 86.6 (2009): 66007.

[2] Frei, A., et al. “Understanding of ultra-cold–neutron production in solid deuterium.” Europhysics Letters 92.6 (2011): 62001.

The use of ultracold neutrons (UCNs) creates new opportunities for experiments to study the fundamental properties of the neutron. The use of superfluid helium for converting cold neutrons into ultracold one is very promising. It is based on the accumulation of UCNs in superfluid helium due to the properties of this quantum liquid.
Our UCN source aims to obtain a record UCN density of 2200 cm-3, which is at least two orders of magnitude higher than the existing UCN density level used in experiments in the world at the moment. To obtain the record ultracold neutron density, unique technologies for creating a new ultracold neutron source have been developed and implemented: obtaining isotopically pure helium-4 to eliminate the neutron-absorbing isotope 3He, obtaining and maintaining superfluid helium at a temperature of 1 K under reactor heat flux conditions, and manufacturing UCN neutron guides with high reflection intensity to increase the amount of UCN delivered to experimental facilities.
By the end of the project, we expect to have an extensive research program in the physics of fundamental interactions established at the new UCN source.

The neutron instrument complex "Neutron Beta Decay" will be located on the beam of polarized cold neutrons on the GEK-3 N0 channel. The installation is designed to measure the asymmetries of neutron beta decay with a relative accuracy of 0.1%. The basis of the installation is a superconducting solenoid that creates a magnetic field in a uniform region of 0.35 T. Electrons and protons appeared during neutron decay move in a magnetic field along magnetic force lines. To select a given angle of electron emission, the magnetic mirror effect is used by creating an area with a stronger magnetic field with an induction value of 0.88 T. The area with high field homogeneity is formed by protons, which can be additionally accelerated by an electric field. An electrostatic system is used for this purpose, which allows raising the voltage in the decay area to 30 kV. Detectors at the input and output of the neutron beam are used to register electrons and protons. To detect electrons, the magnetic field created by the solenoid is deflected downwards to remove electrons from the beam region. A magnetic circuit mounted under the solenoid will be used for this purpose. To deflect protons, the effect of proton drift in crossed electric and magnetic fields is used. At the input of the solenoid are located: a supermirror polarizer, a collimator and a spin-flipper. At the output of the solenoid are located: a polarization analyzer, a neutron detector for beam monitoring, and a neutron beam trap.

The optical scheme of the channel based on two magnetic horns for the formation of neutrino beams with a narrow energy spectrum at the U–70 accelerator complex for the P2O experiment is considered, the far detector of which is located at a distance of 2595 km from the end of the decay channel. To select the required momentum interval of π-mesons, we propose using two dipole magnets with opposite polarity. By rotating the decay part of the channel with respect to the primary proton beam directed to the target, we minimize the content of background neutrinos in the main beam of muon neutrinos (antineutrinos) compared to a direct channel with magnetic horns. The main calculated characteristics of neutrino beams at the far detector of the P2O experiment at an energy of the primary proton beam of 60 GeV are discussed.

The NICA accelerator complex (JINR) includes a Heavy ion linear accelerator (HILAC) designed for injection of heavy ions (with the mass to charge ratio A/Z ≤ 6.35) into the storage synchrotron-Booster. Commissioning sessions with accelerated Xe28+ ions showed insufficient beam intensity of the required heavy ion beam parameters for experiments in the Collider. A multiple injection technology has been developed and is currently being implemented for increase of beam intensity. The paper presents the results of 3-fold and 10-fold injection for heavy ion experiments in the NICA collider.

Double Side Silicon Detector (DSSD) based spectrometer of the DGFRS-2 setup has been applied in a different heavy ion induced complete fusion nuclear reactions leading to formation of superheavy nuclei. Nuclear reactions with $^{48}$Ca, $^{40}$Ar, $^{54}$Cr, $^{50}$Ti projectiles were used [1, 2]. Materials of $^{206}$Pb, $^{nat}$Yb, $^{232}$Th, $^{238}$U, $^{242}$Pu, $^{243}$Am were used as targets. We report about different stability tests during these long term experiment. Radiation damage induced of a change in leakage current values of DSSD detectors are under consideration.Formation of the evaporation residue (ER) registered energy spectrum measured with DSSD focal plane detector is presented. Comparison with the PC-based simulation code for these spectra generation is made for different cases. A specific of application of “active correlation” real-time method is reported in brief too [3]. Review of the design of the DGFRS-2 spectrometer is preceding the main results [4-6].

References.

[1] Yu. Ts. Oganessian et. al., Phys. Rev. C 106, (2022) 024612.

[2] Yu. Ts. Oganessian et. al., Phys. Rev. C 106, (2022) L031301.

[3] Yu. S. Tsyganov et al., Nucl. Instruments and Methods Phys. Res. Sect. A Accel. Spectrometers, Detect. Assoc. Equip. 525, (2004) 213-216.

[4] D. Ibadullayev, Y.S. Tsyganov, A.N. Polyakov, A.A. Voinov and M.V. Shumeiko, JINST, 18 P05010, 2023.

[5] Yu. S. Tsyganov, D. Ibadullayev et. al., Acta Physica Polonica B Proceedings Supplement. 14, (2021) 767-774.

[6] D. Ibadullayevet. al., Eurasian Journal of Physics and Functional Materials 6, (2022) 18-31.

Noble element detectors (two-phase emission detectors, liquid phase-only detectors, etc.) have many applications in modern research.

For example, they are broadly used in dark matter registration, non-standard neutrino interactions searches and even Standard Model processes observation (for example, coherent elastic neutrino-nucleus scattering (CEvNS) studies). Modeling signal generation from these complicated interactions requires precise simulations. The main problem of modeling such phenomena is that various theoretical predictions are inconsistent with each other and compared to experimental data.

In this talk, the current status of NEST: Noble Element Simulation Technique, which is a simulation package based on reasonable empirical models informed by the world's best data on the subject, will be discussed.

Talk will present on the methods used for modeling electronic recoils, nuclear recoils, and quantification of the misidentification of the former as the latter, the primary means of determining the ability to discriminate against residual backgrounds. NEST models results to data will be compared. Also existing work on argon will be discussed.

The ALICE collaboration is committed towards strongly interacting matter studies in proton-proton and heavy ion collisions at LHC, one of the characteristic observables of which are systematic measurements of quarkonia production with the future experiment of ALICE 3. Fast simulations for ALICE 3 showed that studies of charmonia states 1S ($J/\psi \to e^+e^-$) and 1P ($\chi_{cJ} \to J/\psi \gamma$ using a high-resolution electromagnetic calorimeter are attainable. Charmonia reconstruction via $e^+e^-$ decay mode relies on electron identification using a tracking system and an electromagnetic calorimeter. In the current report we demonstrate performance of electron identification procedure on data of the ALICE experiment collected during LHC Run 3 with pp collisions at $\sqrt{s}=13.6$ TeV.

Indirect searches for new physics are possible through studies of Flavor-changing-neutral-current (FCNC) transitions in heavy flavor decays. Several recent results based on 13 TeV (Run-2) and 13.6 TeV (Run-3) pp collisions at the CMS experiment are reported.

CP violation plays a crucial role in our understanding of the universe’s matter-dominated nature. Without CP violation, the Standard Model of particle physics cannot fully explain why the observable universe consists predominantly of matter, as opposed to an equal mix of matter and antimatter. The search for new sources of CP violation is essential for understanding the dynamics that could have led to this imbalance, offering potential insights into physics beyond the Standard Model. This talk discusses the latest results from the CMS experiment at $\sqrt{s}=13\ \text{TeV}$, focusing on CP violation in heavy flavor physics.

CMS results on R(Jpsi) lepton flavor universality observable are reported using two channels of reconstruction of the tau lepton. The measurements use 13 TeV pp collision data from the LHC Run 2.

The narrow resonant-like structures were discovered by three main LHC collaborations (LHCb, ATLAS, CMS) in the di-Jpsi, Jpsi-Psi2S invariant mass spectra suggesting existence of the fully-heavy tetraquarks with a ccc(bar)c(bar) configuration. These new exotic resonances require detailed theoretical and experimental investigation. In this review, the latest experimental results and several theoretical approaches towards physics of new states are presented.

A high statistics search for the $K^+\rightarrow\pi^0\pi^0\pi^0e^+\nu$ decay is performed by the OKA collaboration. No signal
is observed. Two other decays are also studied: $K^+\rightarrow\pi^0e^+\nu$ for normalization and $K^+\rightarrow\pi^0\pi^0e^+\nu$ for the
cross-check. The upper limit set is $BR(K^+\rightarrow\pi^0\pi^0\pi^0e^+\nu)<4.4\times 10^{-8}$ 90% CL, 80 times lower than the one
currently listed by PDG.

Stage 3 of ALICE experiment considers construction of fully new detector based on the novel silicon technologies. New apparatus will widen area of studies of hot and dense QCD matter produced in relativistic heavy-ion collisions for ALICE collaboration. Besides this it will highly improve precision of already obtained results also giving opportunity for differential studies. And one of the goals of future ALICE-3 experiment is precise differential study of open charm production in wide range of transverse momentum.
In this contribution, we present results of feasibility studies for the reconstruction of D-mesons excited states in the decay channels with neutral photons or mesons detected in the large acceptance electromagnetic calorimeter of future ALICE-3 experiment at LHC-HL. Effect of merged clusters in electromagnetic calorimeter is discussed and estimations of reconstructed efficiency, signal to background ratio and required for precise measurements statistics of heavy ions collisions are presented.

We continue studies of the effects previously observed in very central (0-5% class) relativistic heavy-ion collisions where we found that the ratios of the Bjorken energy density fractions, relevant to the identified hadrons, practically are not depending on the collision energy in all cases of open and hidden strangeness [1]. In our new work, we include into the analysis the additional HEP data on the yields of particles containing one, two or three strange quarks. This includes Λ barion and Kos meson , Ξ and Ω hyperons yields measured in Au-Au and Pb-Pb collisions at √sNN = 39 GeV, 200GeV and 2.76 TeV. The particle HEP data spectra were approximated in each case by the Levy functions, and in such way the relevant mean p_t was obtained and used in the calculations of the mean transverse energy density at midrapidity for the particle (i) of interest. The Blast Wave approximation for the spectra shape was also used to compare and to estimate the systematic error of mean p_t and of the relevant mean (dEt/dy)i . Finally, the ratios were obtained of mean (dEt/dy) ϕ /(dEt/dy)i -- for ϕ-mesons and other particles, registered at midrapidity in central A+A collisions. The results are discussed.
The authors acknowledge Saint-Petersburg State University for a research project 95413904
References:
[1] O. Shaposhnikova, A. Marova and G. Feofilov, Open and Hidden Strangeness with Kaons and ϕ-Mesons in Bjorken Energy Density Approach for Central Collisions from SPS to LHC, Physics of Particles and Nuclei, 2024, Vol. 55, No. 4, pp. 1134–1139. © Pleiades Publishing, Ltd., 2024.

I.N. Borzov, 1, 2

1) National Research Centre”Kurchatov Institute”, Moscow, Russia

2) Bogolubov Laboratory of Theoretical Physics, JINR, Dubna, Russia

The charge radii, beta decay half-lives (T1/2) and delayed neutron emission probabilities (Pn) are calculated in the chains of heavy Hg and Pt isotopes. The self-consistent Finite Fermi Systems theory (TFFS) with the Fayans energy-density functional DF3-a [1] is used. It describes well the experimental spectra of single-quasiparticle levels in isotopes near Z=82, N >126. The isotopic dependence of the charge radii has a characteristic kink at crossing of the neutron shell N = 126. The kink indices $\xi$ = $ \delta < r^2 > (128/126)/ \delta < r^2 > (126/124)$, measured in [2,3], are reproduced in the present calculations due to the density gradient pairing and surface terms of DF3-a. In contrast, within the relativistic approach [4] a good description of the radii is achieved mostly due to an inversion of 2ng9/2 and 1ni11/2 levels which exists in the family of relativistic density functionals used in [4] but does not show up in the experimental spectra. Half-lives and Pn values are compared with the compilation of experimental data [5] and with relativistic RHB+RQRPA calculations [6]. Importantly, an inversion of 2ng9/2 and 1ni11/2 levels, does not allow one to simultaneously describe the experimental charge radii and beta decay rates in [4,6]. However, based on the Fayans functional such a description is possible.

1. I.N. Borzov, S.V. Tolokonnikov, Physics of Atomic Nuclei 87, 423 (2024).
2. Z. Yue, A. N. Andreyev, A. E. Barzakh , I. N. Borzov , J. G. Cubiss et.al. Physical Review C 110 (2024), accepted.
3. Y. Hirayama for KISS Collaboration. Phys.Rev. C 106, 034326 (2022); Eur. Phys. J. Spec. Top. 233, 1209–1223 (2024).
4. U.C. Perera, A.V. Afanasjev, P. Ring, Phys. Rev. C 104, 064313 (2021)
5. Reference Database for Beta-Delayed Neutron Emission. https://www-nds.iaea.org/beta-delayed-neutron/database.html
6. T. Marketin, L. Huther, and G. Martínez-Pinedo. Phys. Rev. C 93, 025805 (2016).

The creation of heavy isotopes under extremal pulsed neutron fluences (of $10^{24}$ n/cm$^2$ units) of artificial nucleosynthesis is investigated by means of the dynamical model taking into account the temperature decrease at the matter expansion. The first time the creation of isotopes with neutron excess up to mass A = 255 was obtained and discovered in the Mike experiment [1]. An intensive (n,γ)-activation of the irradiated 238U target ensures the creation of neutron-rich isotopes up to 257Fm. The rapid process is the consistent multiple neutron capture in the target (manufactured from the 238U or more heavy/mixture isotopes as 232Th, 237Np, 238U, 242Pu, 243Am). Creation of transuranium isotopes were investigated during the Plowshare program and some next nuclear tests: Anacostia, Kennebec, Par, Barbel, Tweed, Cyclamen, Kankakee, Vulcan and Hutch [2-5].
In the realized model of the nucleosynthesis (realized during the short time exposition - ~$10^{-6}$ s) it were considered the sequential (n,γ)-neutron captures by mono isotope 238U target and binary (238U + 239Pu)-variant for case of 239Pu injection [6,7]. The model includes the temperature decrease during the adiabatic expansion with index γ = 1.5 at the initial temperature ~20 keV and linear velocity ~190 km/s. Here we simulated the isotope yields for Mike, Anacostia, Barbel, Par, Vulcan and Kankakee experiments. The obtained results indicated on the approximately linear dependence for relations of the isotope yields relative to the obtained neutron fluence [8]. In the work we considered the pairs of neighboring isotopes with atomic masses A=245 and 244, A=246 and 245, A=247 and 246. The relation 246/245 (i.e., yields with masses A=246 and 245) depending on the fluences is the most strong demonstrator of the linear dependence. The most strong confirmation of the roughly linear dependence was obtained for the pure 238U target.

References

[1] Dorn DW. Phys Rev 1962;126:693

[2] United States Nuclear Tests. July 1945 through September 1992. DOE/NV-209-REV 16. September 2015.

[3] Hoff RW, Dorn DW. Nucl Sci Eng 1964;18:110.

[4] Dorn DW, Hoff RW. Phys Rev Lett 1965;14:440.

[5] Balagna JP, et al. Los Alamos Radiohemistry Group. Phys Rev Lett 1965;14:962.

[6] Lutostansky YuS, Lyashuk VI, Panov IV. Bull Russ Acad Sci: Phys 2010;75:533.

[7] Lyashuk VI. Bull Russ Acad Sci: Phys 2012;76:1182–6.

[8] Lyashuk V.I., Results in Physics 2024; 56:107234.

At present, a lot of experimental information has been accumulated on the structure of low-lying excited states in Ge isotopes. Interest in these nuclei is due to the fact that with an increase in the number of neutrons there is a transition between spherical and deformed forms of the nucleus that determine their structure. On the other hand, microscopic calculations show that Ge isotopes are soft in relation to triaxial deformation. In this report, we analyze the properties of low-lying 2+ states in isotopes of 70-88Ge. Calculations were carried out by constructing and diagonalization of the collective quadrupole Hamiltonian. The surfaces of potential energy and mass parameters were calculated in the relativistic mean field model with two parameterization of the energy density functional: PC-PK1 and NL3. The results of the calculations are compared with the experimental data and the results obtained within other approaches.

Fission of heavy nuclei by neutrons at low and intermediate energies (up to 100 MeV) occurs at relatively low angular momenta, which has little effect on the dynamics of nuclear deformation. Due to this, the anisotropy of the angular distribution of fission fragments relative to the direction of motion of incident neutrons is determined by the distribution over the projection K of the spin of the fissioning nucleus onto the deformation axis. This distribution is formed at the fission barrier [1,2]. At sufficiently high excitation energies, the distribution over quantum number K is determined by statistical mechanism [3] and depends on the deformation and temperature of the nucleus. However, due to various difficulties, experimental and theoretical studies of the angular anisotropy of fission fragments by neutrons have not received sufficient attention for a long time. In particular, there is a lack of understanding of the role of the the internal and external humps of fission barrier in the formation of the K-distribution in each fissionable nucleus. Meanwhile, the answer to this question depends on various factors that determine the energy dependence of the nuclear fission cross section for neutrons.
Over the past decade, we have conducted measurements on a neutron time-of-flight spectrometer based on the GNEIS neutron complex at the 1 GeV proton synchrocyclotron of the National Research Centre “Kurchatov Institute” - PNPI (Gatchina) . We have obtained significant data on fission cross sections and the angular distributions of fission fragments for low and intermediate energy neutrons. In addition, we have developed new approaches to the analysis of these characteristics [4,5]. In this paper, we demonstrate that in the area of ​​applicability of the statistical model, it is possible to determine from the angular distribution of fragments which hump of the fission barrier is responsible for the formation of the K-distribution.

[1] A. Bohr. Proceedings of the International Conference on the Peaceful Uses of Atomic Energy, 1955. V. 2. United Nations, New York, 1956. P. 151.

[2] A. L. Barabanov, W. I. Furman. Z. Phys. A 357, 411 (1997).

[3] R. Vandenbosch, J. R. Huizenga. Nuclear Fission. New York, Academic Press, Inc., 1973.

[4] A. S. Vorobyev et al. Phys. Rev. C 108, 014621 (2023).

[5] A. S. Vorobyev et al. Eur. Phys. J. A 60, 117 (2024).

We propose a quark model of nuclear structure where quark correlations lead to nucleon-nucleon correlations and arrangement of them into lattice--like structure. The model is based on the quark model of nucleon structure in which valence quarks are strongly correlated within a nucleon (SCQM) [1]. Nuclei are built by junctions of SU(3) color fields of two quarks of neighboring nucleons. Application of the model to larger collections of nucleons reveals the emergence of the face-centered cubic (FCC) symmetry at a nuclear level where nucleons are arranged in alternating spin--isospin layers [2, 3]. The model of nuclear structure becomes isomorphic to the shell model and, moreover, composes the features of the liquid drop and cluster models. In difference with the shell model, protons and neutrons in our model are strongly correlated. It turns out that building blocks of the nuclear structure are three-nucleon (triton and 3He) and four-nucleon (α-cluster) like configurations. These configurations form inside nuclei virtual triton/3He and α- clusters. We apply the model to analyze nucleosynthesis in stars in the framework of α-clustering. It turns out that the gateway for synthesis of elements heavier than 12C is provided by composition of 5 α- clusters, that corresponds to the excited state 20Ne. Excited 20Ne, than decays to lighter nuclei C, N, O.
Our approach is an alternative to the 3-α Hoyle state that provides the nucleosynthesis of heavier elements occurring naturally in stars.

1. G. Musulmanbekov, in Frontiers of Fundamental Physics, Ed. B. G. Sidharth, (Kluwer Acad./Plenum Pub., New York, 2001), p. 109–120. (2004); PEPAN Lett., Vol., № 5, p. 548-558.
2. G. Musulmanbekov and N.D. Cook, Phys.Atom.Nucl. , 71, 1226 (2008).
3. G. Musulmanbekov, in Exotic Nuclei, Eds. Yu.Peniozhkevich and Yu. Sobolev, World Sci., Singapore, 2017, p. 58; arXiv:1708.04437v2 [nucl-th].

The low-energy multipole spectrum in isotopes 250-260No is investigated in the framework of fully self-consistent Quasiparticle-Random-Phase-Approximation (QRPA) method with Skyrme forces [1,2]. The representative set of Skyrme parametrizations (SLy5, SLy6, SkM* and SVbas) is applied. The main attention is paid to nuclei 252No and 254No, where we have most of the experimental spectroscopic information [3,4]. In addition to low-energy one-phonon collective states (lm=20,22,30,31,32) and their rotational band, the isomeric states are inspected. In general, a good agreement with the experimental data is obtained. Some K-isomers in these nuclei are inspected. It is shown that, in the chain 250−260No, features of 252No and 254No exhibit essential irregularities caused by a shell gap in the neutron single-particle spectra and corresponding break of the neutron pairing. The low-energy pairing-vibrational Kπ = 0+ state is predicted.

[1] P.-G. Reinhard, B. Schuetrumpf, and J. A. Maruhn, Comp. Phys. Commun. 258, 107603 (2021).

[2] A. Repko, J. Kvasil, V.O. Nesterenko and P.-G. Reinhard, arXiv:1510.01248[nucl-th].

[3] R.-D. Herzberg and P.T. Greenlees, Prog. Part. Nucl. Phys. 61, 674 (2008).

[4] R.-D. Herzberg, arXiv:2309.10468[nucl-ex].

[5] F.L. Bello Garrote et all, Phys. Lett. B834, 137479 (2022).

Muonic molecular ions He-p-µ and Li-p-µ are studied numerically in the variational approach. Using the complex coordinate rotation method we calculate energies of resonant states. These molecular systems may be of interest for studying low-energy fusion reactions.

The structure of exotic neutron-rich nuclei is one of the main science drivers in contemporary nuclear physics research [1]. The new measurements of pygmy dipole (PDR) and giant dipole (GDR) resonances in neutron-rich nuclei have sparked advancements in nuclear models. The quasiparticle random phase approximation, utilizing the self-consistent mean-field derived from Skyrme effective interactions, is a widely used tool for describing the PDR and GDR. This approach made it possible to a successful description of the properties of low-lying states and the characteristics of giant multipole resonances in spherical nuclei [2,3].
Due to the anharmonicity of vibrations there is a coupling between simple particle-hole configurations and more complex states [4,5]. As an illustration, we study the properties of the low-lying dipole states in the neutron-rich Ca and Ni isotopes [6,7]. This reveals a number of characteristic features of the low-energy E1 modes. The effect of the low-energy E1 strength on the electric dipole polarizability is discussed [5]. The correlations between the electric dipole polarizability, the symmetry energy, and neutron skin thickness are studied [8].
The research was supported within the framework of the scientific program of the National Center for Physics and Mathematics, topic no. 6 “Nuclear and Radiation Physics” (stage 2023-2025).

[1] A. Zilges, D.L. Balabanski, J. Isaak, and N. Pietralla, Prog. Part. Nucl. Phys. 122, 103903 (2022).
[2] N. Paar, D. Vretenar, E. Khan, and G. Colò, Rep. Progr. Phys. 70, 691 (2007).
[3] E.G. Lanza, L. Pellegri, A. Vitturi, and M.V. Andrés, Prog. Part. Nucl. Phys. 129, 104006 (2023).
[4] V.G. Soloviev, Theory of Atomic Nuclei: Quasiparticles and Phonons. Bristol/Philadelphia 1992.
[5] A.P. Severyukhin, N.N. Arsenyev, and N. Pietralla, Phys. Rev. C. 104, 024310 (2021).
[6] N.N. Arsenyev, A.P. Severyukhin, V.V. Voronov, and N.V. Giai, Phys. Rev. C. 95, 054312 (2017).
[7] N.N. Arsenyev, A.P. Severyukhin, V.V. Voronov, and N.V. Giai, Phys. Part. Nucl. 50, 528 (2019).
[8] N.N. Arsenyev, and A.P. Severyukhin, Moscow Univ. Phys. Bull. 79, 200 (2024).

Light mesons tend to cluster near certain values of mass. It is interesting to notice that such a degeneracy can be described using dynamical $O(4)$-symmetry, like in the hydrogen atom. The meson mass spectrum can be well approximated by linear Regge trajectories of the kind $M^2=a l+b n_r+c$, where $l$ and $n_r$ are angular momentum and radial quantum number, and $a$, $b$, $c$ are coefficients. Such a spectrum arises naturally within the hadron string models. Using 2024 data from the Particle Data Group, a fit for $M^2(l,n_r)$ was performed. Our analysis seems to confirm that $a\approx b$ in the light non-strange mesons, i.e., their masses depend on the sum $l+n_r$ as prescribed by the hydrogen-like $O(4)$-symmetry. Using the semiclassical approximation, we discuss which kind of hadron string models are more favored by the experimental data.

In my talk I will review the hydrodynamical approach to the description of the gravitational chiral anomaly in spacetimes with a non-trivial Ricci tensor proportional to the cosmological constant (so-called Einstein manifolds) and discuss an alternative derivation of the Unruh effect in curved spacetime as a non-trivial consequence of the hydrodynamical description of the axial current.

Masses of the triply heavy tetraquarks of all flavor compositions are calculated within the relativistic quark model, based on the quasipotential approach and QCD. Tetraquark is treated as a bound state of the nonobservable non-pointlike diquark and antidiquark. The relativistic quasipotential equation takes into account all relativistic corrections (both spin--dependent and spin--independent) and the internal structure of the diquarks via the insertion of calculated diquark--gluon form-factors. The calculated masses of tetraquarks are compared with the strong fall--apart decay thresholds into pair of heavy and heavy--light mesons. The states that lie slightly above or under such thresholds and thus could be observed as narrow resonances in other decay modes are determined.

We show that there is a relationship between hydrodynamic effects in flat space and effects in a gravitational field. Moreover, this connection is valid at the quantum level in the case of quantum anomalies. In particular, we find in an accelerated and vortical medium a transport effect directly related to the gravitational chiral anomaly. The general theorem about this relationship is explicitly verified by comparing two independent calculations, quantum-field for the anomaly, and quantum-statistical for the transport coefficients, for the case of massless fields with spins 1/2 and 3/2.

A detailed analysis of the electromagnetic form factors of nucleons could help in studying weak interactions with neutrinos due to the coincidence of the vector parts of the electromagnetic and weak currents. There are several theoretical approaches to study these form factors. In this talk the model of extended vector meson dominance with families of $\rho$ and $\omega$ mesons with their radial excitations is discussed. The nucleon electromagnetic form factors in space- and time-like regions are studied taking into account new experimental data. A detailed description of the behavior of form factors, as well as the values ​​of the electric and magnetic radii of the nucleon and the Zemach radii are obtained. The model discussed is an upgrade of the model [1].

[1] B. V. Martemyanov, Amand Faessler, and M. I. Krivoruchenko "Electromagnetic form factors of nucleons in the extended vector meson dominance model", Phys. Rev. C 82, 038201 (2010).

We revisit the production of vector portal mediators, dark photons with masses 0.4-1.8 GeV, via inelastic proton bremsstrahlung. For the first time, we add the contribution associated with the Pauli electromagnetic proton form factor and obtain new splitting functions according to the factorization procedure originally proposed by Altarelli and Parisi. We also demonstrate the significance of the found corrections numerically and update sensitivity estimates for the T2K, DUNE, and SHiP experiments. The talk is based on arXiv preprints 2409.11089, 2409.11386.

The cross sections for the production of single and paired dileptons in electron-positron annihilation are calculated within the framework of quantum electrodynamics. Both one-photon and two-photon mechanisms of electron-positron annihilation with subsequent production of leptons are considered. The formation of both singlet and triplet states of dimuonium and ditauonium is studied. The production cross sections are constructed taking into account relativistic corrections in the production amplitude and the wave function of the bound state, as well as the binding energy of leptons in the bound state.

The Belle II experiment at the SuperKEKB electron-positron asymmetric energy collider is a substantial upgrade of the Belle experiment, which has been running at KEK for over a decade. For now, Belle II recorded 424\fb of data aiming for an unprecedented sample of 50\ab, a factor of 50 more than its predecessor. With this data set, Belle II will be able to explore flavor physics with B and D mesons, and τ leptons and search for new physics with unmatched precision. We discuss selected recent results from the Belle II experiment.

A collaboration of MISIS, MEPhI, SINP of MSU and LPI of RAS based on emulsion detectors has developed and is actively using in Russia a scientific engineering and technological concept of muonographic work, the created equipment and software. A successful series of works on muonography of large objects has been completed: assessment of the technical condition of the equipment of the distillation column of the oil refinery by order of the Swiss company Sulzer, muonographic surveys of the mine of the Geophysical Service of the Russian Academy of Sciences in Obninsk, inertial drums of the tire stand of the Research Institute of the Tire Industry, etc. The muonography method was used to carry out the first surveys of cultural heritage sites - a unique archaeological site in the Naryn-Kala fortress (Derbent); buildings and territory of the Holy Trinity Danilov Monastery in Pereslavl-Zalessky - the work was awarded the Makaryev Nature Science Prize in 2022; previously unknown cavities were discovered in the cave church of the Pskov-Pechersky Monastery; A muonographic survey of the territory and hidden structure of the buildings of the Spaso-Kamenny Preobrazhensky Monastery founded in 1260 on Kamenny Island in Lake Kubenskoye was carried out. The author's methodological approaches and technical solutions using emulsion track detectors, as well as the results of the conducted investigations, are of great importance from the point of view of further implementation prospects of an effective, economical and environmentally safe method of muonography, as a method of non-destructive study of the internal structure of natural, industrial and architectural objects and for the creation of monitoring systems for problem objects to minimize the consequences of possible natural and man-made disasters for the population, infrastructure and the environment.

For experiments on searching for rare underground events, such as detection of solar neutrinos, neutrinos from supernovae, neutrinoless beta decay, the main problem is the background variation. Regardless of the detector power supply, two types of backgrounds can be specified: muons and natural radioactivity of construction materials, rock, as well as a variable component of radioactivity - underground gases. Emissions of radioactive gases can be a consequence of both impending earthquakes and changes in local humidity and pressure. We have created an autonomous station capable of monitoring environmental parameters such as temperature, humidity, pressure, CO2 concentration, radon, density of positive and negative air ions, and measuring vibration levels in different frequency ranges. The universal complex displays all parameters online on the monitor screen and saves them to a file for further processing. A diagram of the developed complex and the limits of the measured parameters are presented. The measurement results for the underground room of the experimental hall of 40 $\text{m}^3$ at a depth of 10 m are given.

Detectors based on organic crystals of trans-stilbene and paraterphenyl are the most effective for simultaneous registration of mixed gamma-neutron fields in the range of 0.1 – 20 MeV, which is an integral part of scientific and dosimetric measurements in nuclear power engineering and nuclear medicine. Currently, organic crystal detectors are not mass-produced in Russia, although in the Soviet Union there were produced in an industrial scale. In 2022-2023, employees of the Federal Research Institute “Crystallography and Photonics” of the Russian Academy of Sciences developed the original technology and produced samples of paraterphenyl and trans-stilbene crystals, which have been used for the manufacturing of the detectors prototypes. To test the scintillation properties of the detectors, the method for determining the light output was used, including the experimental and simulation stages. Light-output measurement and energy calibration was done by determining the location of the Compton edge when irradiating a sample with standard gamma sources. The position of the Compton edge was calculated by differentiating the energy spectrum. Comparing the parameters of the Compton edges for different samples the relative light outputs of the samples have been obtained.

The work was supported by the Ministry of Science and Higher Education of the Russian Federation (grant No. 075-15-2024-637).

Method of measurement and result of processing of the 213Po α-active isotope half-life data measured in long-run continuous measurement with the underground low-background TAU-3 set-up are described. The set-up consists of two scintillation NaI(Tl) 150x150 mm detectors and double-layer (hlayer=1 mm) plastic scintillator detector (PCD) with d=18 mm. Source of the ...213Bi→213Po… decays placed between the PSD layers. The half-life calculated from a decay curve. The curve constructed from delay values between β- and α-pulses detected by the PSD.
Two methods used for the event selection. The PSD pulses coincided in 16 mcs time window selected in the first case (double coincidences). Additional pulse of the NaI-SD detected γ- quantum from the 213Bi decay used in the second case for a validation of the 213Po birth and decay (triple coincidences). The values T1/2=3.6970±0.0005 mcs for the double coincidences and T1/2=3.6772±0.0005 (statistic)±0.005 (system) mcs for the triple coincidences were obtained 213Po half-life. Possible reasons of the result difference were discussed.

The main reaction used to detect Core-collapse Supernova neutrinos in physical experiments is the inverse beta decay reaction. Positrons produced in the reaction pass through a scintillator only a few centimeters thick. For the Baksan Underground Scintillation Telescope (BUST) detector, which has a modular structure, the inverse beta decay reaction appears as a single trigger of an individual counter. The problem of detecting the reaction from neutrinos in the counter is due to a large background of single events with different natures. The main sources of background single events include:
- single muons penetrating through the detector's shielding;
- high-energy neutrons producing unstable isotopes in the detector's scintillator;
- neutrons participating in elastic collisions with target protons;
- unstable isotopes created in cascades through the inelastic interaction of muons with the detector's materials;
- local radioactivity;
- random counter triggers.
This work discusses the methodologies for evaluating each of the background components currently used in processing the experimental data of the BUST detector.

We consider applications of the deformation procedure to two-soliton solutions of the sine-Gordon model. We analyze the resulting kink-antikink configurations of other field-theoretical models.

The project assumes that in one installation two traps are installed on the same axis: material and magnetic. By rotating the trap system around an axis, it is possible to carry out gravitational capture of UCNs either into a material or into a magnetic trap. Thus, on one installation it is possible to compare the material and magnetic storage of UCNs under the same conditions. It is also important to note that these two measurement methods differ methodically: in a material trap, the neutron lifetime is obtained as a result of extrapolation, while in a magnetic trap it is measured directly. Such a measurement scheme will make it possible to get rid of a number of systematic uncertainties in measurements with different traps and is proposed for the first time. The gravitational capture of UCNs in a magnetic trap proposed in the project is a fundamentally new approach that has never been implemented before. Possible systematic effects due to neutron depolarization and the turbine effect in a magnetic trap are considered. The experiment can be carried out on the ultracold neutron source under construction at the PIK reactor. The design of the installation and the plan for its location in the main reactor hall have been developed. The study has been carried out with the support from the Russian Science Foundation, grant no. 23-22-00169, https://rscf.ru/project/23-22-00169/.

Dear colleagues, It's a pity, my co-authour L.Tkachev has pointed out that the results I wanted to present were not complete, since the results of analysis of the events caused by gamma quanta were not included. I am forced to withdraw as the co-authors were the main designers of the Scintillator fast trigger system on the data from which the results were obtained 7 years ago.
S.K. Slepnyov.

The deuteron-proton elastic scattering process is considered in the relativistic
expansion framework. Four reaction mechanisms are taken into account: one-nucleon exchange,
single-scattering, double-scattering terms, and term with delta-isobar in the intermediate state.
Each of these mechanisms contributes into the reaction amplitude. The calculations for the
differential cross section and a number of polarization observables are performed in a GeV-energy range for the special case when the scattering angle is equal to 180 degrees in the center of mass.
The results are given for various deuteron wave functions: Paris, CD Bonn, and Gross.

The particle identification system for the barrel region of the ePIC experiment at the future Electron-Ion Collider will be based on a DIRC detector. DIRC stands for Detection of Internally Reflected Cherenkov light, and this technology is planned to be used for charged particle identification for momenta up to at least 6 GeV/c. The DIRC technology is sensitive to the optical properties of the materials comprising the optical system of the detector. This contribution presents simulation studies of optical properties for fused silica, NLAK3, and optical sapphire glass.

Recent multi-messenger observations suggest that high-energy neutrinos may be produced close to central black holes in active galaxies. These regions may host dark-matter (DM) spikes, where the concentration of DM particles is very high. Here we explore the contribution of the DM annihilation to the target photons for the neutrino production, proton-photon interactions, estimate the associated neutrino spectrum and figure out possible future tests of this scenario.

One of the features of general relativity is the possible existence of space-time with a nontrivial topological and casual global structure . The real three-dimensional space might in principle be multiply connected and there might exist wormholes in it.
The presence of a wormhole leads to the appearance of corrections to the Coulomb law. In the present work, an exact solution of the Laplace equation for a flat space with a wormhole whose mouths are spheres is found. It is shown that a point charge is attracted to the wormhole at all points in space except for the plane of symmetry. An analogy is noted between the attraction of a charge to the mouth of a wormhole and the attraction of a charge to a polarizable body. A freely moving charge experiences acceleration due to the presence of attraction to the mouth of a wormhole, which leads to the appearance of electromagnetic radiation. The paper presents estimates of the power of electromagnetic radiation for a charge flying near the mouth of a wormhole. The motion of the mouth through the plasma leads to the appearance of inhomogeneities in the distribution of matter and can serve as an additional source of cosmological disturbances that significantly affect the rate of formation of galaxies.

Scintillation detectors are successfully used to register fast neutrons in the presence of background gamma radiation. However, when scintillation detectors operate near particle accelerators, a problem arises due to the presence of a magnetic field near the accelerator.
In this paper we investigate the influence of the magnetic field of the HELIS accelerator facility on the parameters of scintillation detector signals and on the efficiency of separating signals from neutrons and gamma quanta. Each detector contains organic monocrystal p-terphenyl and a Hamamatsu R6094 photomultiplier tube. The signals from the photomultiplier tube outputs are digitized using a CAEN DT5730 Digitizer.
The gamma-quantum sources Cs-137 and Co-60 were used to study the change in the amplitude and shape of the detector signals at different locations of the PMT dynode system relative to the magnetic field. The presence of a magnetic field leads to a decrease in the amplitude of the signals and distortion of their shape.
Using the Cf-252 neutron source, the dependence of the efficiency of signal separation from neutrons and gamma quanta on the magnetic field strength was studied. In the absence of a magnetic field, the coefficient of efficiency of signal separation Figure of Merit is FOM=1.5. At a magnetic field of 0.5 mT, the efficiency of signal separation from neutrons and gamma quanta (detectors without a magnetic shield) decreases to FOM=1, and at a field of ≈ 1 mT, it becomes impossible to separate the signals. The use of PMTs with magnetic shields allows neutrons to be registered without deterioration of the efficiency of signal separation in magnetic fields up to 5 mT.
It has been demonstrated that scintillation detectors with magnetic screens effectively register fast neutrons at the HELIS accelerator facility.

The problem of diagnostics of electron reaction products obtained in experiments on particle acceleration by a laser field was solved. Accelerated electrons were obtained by the interaction of a laser pulse with a flowing gas target. The central wavelength of the laser pulse is 800 nm, the duration is about 50 fs, and the repetition rate is 10 Hz. The energy on the target reaches 60 mJ. Due to the fact that the diagnosis by registering gamma quanta is difficult due to the multiple nature of the particles huge number birth within a short period of time (50 fs), the diagnosis was carried out through the photoneutron birth channel from the target-converter by the time-of-flight method. Neutrons were recorded using cylindrical scintillation detectors based on crystalline trans-stilbene with dimensions of 20x20 mm (1 piece) and 40x40 mm (2 pieces), located at distances from 1.5 to 2.7 m from the converter target.

Data accumulation was carried out synchronously with the laser operation. The response of all three detectors was recorded for each pulse. Next, neutron events were selected by analyzing the detectors response according to the pulse shape and the time of the pulse registration relative to the laser pulse. To increase the threshold for neutron energy registration, digital signal processing was used, which made it possible to detect a response from neutrons against the background of a decrease in the overload of the detector with a primary pulse of gamma quanta. This made it possible to reduce the time threshold for neutron registration to 200 ns on a fixed detector base, which is equivalent to the threshold for neutron registration of 250, 450, 1050 keV, respectively.

Distributions of candidate events by registration time were constructed taking into account the released energy, which makes it possible to estimate the spectrum of registered neutrons, which makes it possible to estimate the energy of processes during particle acceleration by a laser field.

An simulation for two main reactions of fast neutron and boron-10 inteaction in anode wire coating

of gas-discharge tube counter is performed.

Moving of secondary nuclei ${^4}He$ и ${^7}Li$ within coating is considered.

Residual energy of nuclei is calculated taking into account reaction kinematics.

It was found that a condition for a both nucleus exit from anode to counter gas must be

claiming enough high energy above 3 MeV and small wire external radius below $20\mu m$.

Nuclear track emulsion (NTE) remains a universal and cost-efficient detector. The application of NTE is especially well grounded where tracks of nuclear particles cannot be reconstructed using electronic detectors. At the JINR Nuclotron the BECQUEREL experiment [1] is performed a program of irradiation of NTE stacks in the beams of relativistic isotopes of beryllium, boron, carbon and nitrogen, including radioactive ones to study their cluster structure. The NTE technique allows one to observe the 3D images of few-body ensembles originated in peripheral collisions and explore the fragmentation of the relativistic nuclei down to the most peripheral interactions - nuclear “white” stars [2].

The competitive character of the novel NTE is proved in measurements of slow α particles and heavy ions (summarized in [3]). The possibility of α spectrometry was verified and the atom drift effect is established in measurement of decays of 60 MeV 8He nuclei implanted in NTE [4]. Correlations of α particles in splitting of 12C nuclei by 14.1 MeV neutrons [5] as well as 7Li and 4He nuclei produced in 10B breakup by thermal neutrons in boron-enriched NTE [6] are studied. NTE samples were irradiated with relativistic and slow Kr and Xe ions [2,7,8]. Surface irradiations of NTE samples were performed with automatic movement of the 252Cf source [9].

Classic observations of fundamental importance presented in “The Study of Elementary Particles by the Photographic Method” by C. H. Powell, P. H. Fowler and D. H. Perkins [10] can serve as a model of clarity in our time. Our research is implemented in keeping with this tradition by state-of-art means. The rich collection of videos and images of the nuclear few-body processes gathered at the Web site is presented [1]. In terms of applications they are relevant for the development of advanced systems of automatic search for nuclear interactions, as well as for university education.

1. The BECQUEREL Project WEB site: http://becquerel.jinr.ru/

2. http://becquerel.jinr.ru/movies/movies.html

3. P. I. Zarubin “Recent applications of nuclear track emulsion technique” Phys. At. Nucl., 2016, 79, 1525-1535; DOI: 10.1134/S1063778816130093.

4. http://becquerel.jinr.ru/miscellanea/8He/8He.html

5. http://becquerel.jinr.ru/miscellanea/DVIN/dvin11.html

6. http://becquerel.jinr.ru/miscellanea/IBR-2/IBR-2.html

7. http://becquerel.jinr.ru/miscellanea/IC-100/IC-100.html

8. http://becquerel.jinr.ru/miscellanea/U400M/U400M.html

9. http://becquerel.jinr.ru/miscellanea/Prague-dosimetry/Prague-dosimetry.html

10. http://becquerel.jinr.ru/text/books/POWELL.pdf

The results of measurements of charge losses at detection of heavy xenon ions with detectors based on boron carbide (SiC) and silicon (Si) are presented. It is shown that the measured values of charge losses (amplitude defect) from the true energy of Xe ions for Si and SiC detectors are 20 and 40%, respectively. These results are due to the significantly shorter lifetime of charge carriers created by the particle in SiC compared to silicon. When using SiC detectors, this leads to a significantly greater recombination of electron-hole pairs in the region of the so-called “plasma filament”, which is formed in the ion track.

The new hybrid system of the forward detectors called the Fast Interaction Trigger (FIT) was developed and integrated with the ALICE experimental setup at the LHC during LS2 (2019 – 2022). It consists of separate arrays of counters – FT0, FV0 and FDD, using different techniques of charged particles detection. FIT is the primary online ALICE trigger. It produces low latency (<425 ns) minimum bias, vertex, and centrality triggers – the fastest (LM0) triggers of the ALICE experiment. The different FIT trigger combinations are used for online luminosity and background monitoring during pp and Pb-Pb collisions. FIT front-end electronics (FEE) allow events to be processed at every LHC clock period (25 ns), enabling both triggered and continuous readout modes. The general offline purposes of FIT are the precise collision time, centrality, event-plane determination and veto for diffractive and ultra-peripheral heavy-ion collisions. The first is also used as a reference for PID with TOF detector.

Since the beginning of Run 3, FIT has been performing very well. The FT0 detector shows outstanding time resolution of about 17 ps for pp and 4 ps for Pb-Pb collisions, good vertex purity, and correlation with ALICE trackers. Moreover, FIT became ALICE’s main online luminometer and has been the reference for experiment coordination. In the presentation, we describe the FIT construction, layout, and our experience of operation during the first two years of Run 3.

Cathode Strip Chambers (CSCs) are used in the muon system of the CMS experiment (CERN). There are four muon stations on both endcaps consisting of 540 CSCs operating with 40%Ar+50%CO2+10%CF4 gas mixture. The chamber longevity study is particularly important in anticipation of the future LHC upgrade into HL-LHC and the scheduled upgrade of the CMS detector which will result in a significant background increase in the forward region.
The CSC longevity is studied with two CMS CSCs ME1/1 and ME2/1 at the Gamma Irradiation Facility (GIF++, CERN), where the charge accumulation rate is about 30 times higher than that at the HL-LHC conditions. Now the accumulated charge for these CSCs is close to the triple HL-LHC charge value. During the irradiation three working gas mixtures were studied: 40%Ar+CO2 with different fractions of CF4, namely 10%, 5% and 2%. The tests did not show any degradations of the chamber performance.
Search on reduction or possible replacement of the CF4 in the working gas mixture is also ongoing in a laboratory, including the longevity studies with small CSC prototypes.

A gaseous beam monitor utilizing gas electron multiplier (GEM) and pixel sensors is being developed for the Cooling Storage Ring (CSR) external-target experiment (CEE) at Heavy Ion Research Facility in Lanzhou (HIRFL). The beam monitor is mainly used to track each beam particle, providing an accurate reconstruction of the primary vertex of the collision. Two generations of the pixel sensors (named Topmetal-CEE) were produced, with the second generation having much-improved noise performance over the first one. The readout electronics includes two chip carrier cards, two front-end cards, and a readout and control unit. This talk presents the design and performance of two prototype detectors, featuring two generations of the pixel sensors, respectively. In particular, the results of the tests with heavy-ion beams and laser beams are presented, showing a spatial resolution of better than 50 $\mu$m and a time resolution of better than 15 ns. The studies demonstrate that the spatial and time resolution of the prototype satisfies the design specifications.

The world’s largest vertical coordinate detector TREK is assembled at MEPhI, it consists of 264 drift chambers and covers an area of 250 m$^2$. TREK along with Cherenkov water calorimeter NEVOD can estimate the specific energy deposit in water of muon component in inclined extensive air showers (EAS). This is necessary to resolve the muon puzzle: the deficit in the number of cosmic ray muons calculated using hadron interaction models compared with observations at energies greater than $10^{17}$ eV.
The need to study the response of TREK to passing muon bundles necessitated modeling of the multi-wire drift chamber along with its associated amplifier circuit, the building blocks of TREK. First, the drift chamber was modeled, using Geant4 software package which allows simulation of particle passing through both the chamber and the entire detector, including the building. Then the drift chamber’s response was simulated using Garfield++. The time-based current response of this drift chamber model was then translated into LTspice, a program based on spice-technology, in which the amplifier circuit AMP-04 was simulated. This sequential modeling showed quite close results, such as the efficiency of the signal channels was shown to be 98.6±0.2%, compared with the corresponding experimental measurement of 97.9±1.1%. This and similar comparison of other parameters will be presented at the conference.
This sequence of simulations allows modelling of expected results of cosmic ray muon bundle registration, as well as collection of datasets for reconstruction methods based on machine learning.

In our work we investigated application of artificial neural networks to event-wise analysis of heavy ion collisions data. We focused on solving the problem of impact parameter evaluation and estimation of collision vertex coordinate, using simulated data from a microchannel plate detector (MCP) [1] for potential use in NICA collider experiments [2]. Our study reveals, that such a technique can be utilized to estimate collision parameters quite accurately from raw detector data [3, 4, 5] based on QGSM
event generator [6], specifically from spatial distributions of particles and time-of-flight distributions.

However, ANNs results are highly dependent on the model of event generator used to create the dataset. Repeating the experiments with data from alternative generators [7, 8] yielded different results. Despite this model dependence of the ANNs, we discuss the way they can be utilized to build model-independent algorithms. Moreover, we have shown that the detector parameters providing the best reconstruction of the event parameters do not depend on the Monte-Carlo model of the event, and, therefore, are more likely to be optimal in future experiments.

The authors acknowledge Saint-Petersburg State University for a research project 95413904.

References:

[1] A.A.Baldin, G.A. Feofilov, P. Har'yuzov, and F.F. Valiev,
// Nucl. Instrum. Meth.A 2020, V.958,P.162154. https://doi.org/10.1016/j.nima.2019.04.108

[2] https://nica.jinr.ru/

[3] K.A. Galaktionov, V.A. Roudnev, and F.F. Valiev, Neural network approach to impact parameter estimation in high-energy collisions using the microchannel plate detector data,
// Moscow University Physics Bulletin 2023, V. 78, P. S52-S58

[4] Galaktionov K.A., Roudnev V.A., Valiev F.F. Artificial Neural Networks Application in Estimating the Impact Parameter in Heavy Ion Collisions Using the Microchannel Plate Detector Data: Physics of Atomic Nuclei.
//Phys. At. Nucl. 2023 V.86(6), P.1426-1432. https://doi.org/10.1134/S1063778823060248

[5] Galaktionov, K., Roudnev, V., Valiev, F., Application of Neural Networks for Event-by-Event Evaluation of the Impact Parameter,
// Physics of Particles and Nuclei 2023 ,V. 54, P. 446-448

[6] Amelin N. S., Gudima K. K., Toneev V. D. Ultrarelativistic nucleus-nucleus collisions within a dynamical model of independent quark - gluon strings // Sov. J. Nucl. Phys. 1990. V. 51(6), P. 1730-1743

[7] Werner, Klaus and Liu, Fu-Ming and Pierog, Tanguy Parton ladder splitting and the rapidity dependence of transverse momentum spectra in deuteron-gold collisions at the BNL Relativistic Heavy Ion Collider
// Physical Review C 2006, V. 74

[8] Aichelin, J. and Bratkovskaya, E. and Le Fèvre, A. and Kireyeu, V. and Kolesnikov, V. and Leifels, Y. and Voronyuk, V. and Coci, G. Parton-hadron-quantum-molecular dynamics: A novel microscopic n-body transport approach for heavy-ion collisions, dynamical cluster formation, and hypernuclei production
// Physical Review C 2020, V. 101

The TAIGA-HiSCORE setup is an array of wide-angle Cherenkov detectors. It contains more than a hundred stations located in the Tunka Valley. The effective area of ​​the setup is about 1 sq. km. The HiSCORE setup is designed to register cosmic particles and gamma quanta with TeV energies. Each station records a large amount of data, including the signal arrival time and its amplitude. Primary data analysis includes the reconstruction of EAS parameters. These are the EAS axis direction, the type of primary particle, and its energy. In this report, we propose using the deep learning method to reconstruct the EAS parameters recorded by HiSCORE. Using the example of determining the EAS axis direction, we will consider two approaches based on deep neural networks. One of them is based on representing a set of time stamps as an image and processing such data using convolutional neural networks. The other approach uses fully connected deep neural networks to solve the regression problem based on time stamps. Both approaches are shown to yield results comparable to traditional data analysis methods.

The radiation hardness of optical materials and stability of optical properties in aggressive radiation environment is one of crucial issues for the detectors based on the detection of Cherenkov light, such as DIRC(s) at the Electron-Ion Collider at the Brookhaven National Laboratory. This contribution presents the results of radiation hardness tests performed with the following optical materials: fused silica, optical sapphire glass, and BaF. The irradiation was performed on the Microtron MT-25 at Flerov laboratory of Joint Institute for Nuclear Research (JINR, Dubna, Russia), and theoretical calculations of the consumed dose are presented. The light transmittance over a wide range of wavelengths was tested for the consumed doses up to 20 MRad.

We present measurements of charmonia production cross sections in e+e- annihilation at center-of-mass energies from 3.81 GeV to 4.95 GeV at BESIII. The number of observed vector states in this energy region exceeds that of the predicted vector charmonium states. These features suggest that some of these supernumerary vector states are candidates of an exotic nature. To clarify the nature of these states and to distinguish between the different theoretical models, precise measurements of the production cross section and of the resonance parameters are essential.

The J/psi charmonium state can decay
to the same final states through either
strong or electromagnetic mechanism.
Theoretical models predict rather different
values of the relative phase difference
between the two amplitudes. The BESIII
experiment has performed an energy scan
of the process e+e- -> J/psi -> phi eta
in the vicinity of the J/psi peak.
In this talk we report the determination
of the phase difference between strong
and electromagnetic amplitudes from the
lineshape scan of the J/psi resonance.

We report measurements of the $e^+e^− \rightarrow B\bar{B}, B\bar{B}^*,$ and $B^*\bar{B}^*$ cross sections at four energies, 10653, 10701, 10746 and 10805 MeV, using data collected by the Belle II experiment. We reconstruct one $B$ meson in a large number of hadronic final states and use its momentum to identify the production process. In the first 2 − 5 MeV above $B\bar{B}^*$ threshold, the $e^+e^− \rightarrow B^*\bar{B}^*$ cross section increases rapidly. This may indicate the presence of a pole close to the threshold.

A study of the hadrons production in $e^+e^-$ annihilation at low energies provides important information about interactions of light quarks and spectroscopy of their bound states.
Precise measurements of the total hadronic cross section, characterized by the ratio R, is needed for the calculation of the contribution of the hadronic vacuum polarization to the muon anomalous magnetic moment. It should be noted that at present the accuracy of the theoretical calculations of the muon (g-2) via the Standard Model is dominated by the precision of the hadronic contribution while an ambiguity in the theoretical results exists due to considerable difference between experimental data from different experiments. This reports describes status and prospects of the hadronic cross sections measurements at Belle II experiment via ISR approach. A measurement of the $e^+e^− \to \pi^+\pi^−\pi^0$ cross section in the energy range from 0.62 GeV to 3.5 GeV based on 191 fb$^{−1}$ of integrated luminosity is considered in details.

We report measurement of the $B_s^0$ absolute branching fractions $Br(B_s^0 \to D_s^{\pm} X)$, $Br(B_s^0 \to D^0/\bar{D}^0 X)$, and $Br(B_s^0 \to D^{\pm} X)$. The results are based on a sample of 121.4 fb$^{-1}$ collected at the $\Upsilon(10860)$ resonance by the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. We perform full reconstruction of one $B_s^0$ meson in $e^+e^- \to \Upsilon(10860) \to B_s^{*} \bar{B}_s^{*}$ events and measure yields of $D_s^+$, $D^0$, and $D^+$ mesons in the rest of the event. We obtain $Br(B_s^0 \to D_s^{\pm} X)$ = (68.6 $\pm$ 7.2 $\pm$ 4.0)%, $Br(B_s^0 \to D^0/\bar{D}^0 X)$ = (21.5 $\pm$ 6.1 $\pm$ 1.8)%, and $Br(B_s^0 \to D^{\pm} X)$ = (12.6 $\pm$ 4.6 $\pm$ 1.3)%, where the first uncertainty is statistical and the second is systematic. The results for $Br(B_s^0 \to D_s^{\pm} X)$ and $Br(B_s^0 \to D^0/\bar{D}^0 X)$ are compatible with previous Belle measurements, the $Br(B_s^0 \to D^{\pm} X)$ is measured for the first time.

The Belle and Belle II experiments have collected a unique sample of data at centre-of-mass energies above the $\Upsilon(\text{4S})$ resonance. We present several results related to hadronic transitions between bottomonium states such as $\Upsilon(\text{5S}) \to \Upsilon(\text{1S,2S})\eta$, $\Upsilon(\text{5S, 10753}) \to \Upsilon(\text{1S,2S})\pi^+\pi^-$, $\Upsilon(\text{5S}) \to h_b(\text{1P,2P})\pi^+\pi^-$, and $h_b(\text{1P,2P}) \to \Upsilon(1S)\eta$.

Latest CMS results on spectroscopy of beauty strange baryons are reported, including new decay modes and studies of excited states. The analyses use pp collision data at 13 TeV.

Decays of $B_c^+$ meson involving a charmonium resonance are studied. Both Run-2 and Run-3 pp collision data are used to improve the sensitivity and accuracy of the measurements.

After a brief review of Gribov copy effects in Landau gauge we present recent results of studies of these effects in the Maximal Abelian gauge in lattice gluodynamics. In particular, we show that one can find Gribov copies with nice decomposition of the static quark potential into monopole and monopoleless components.

The study of theories related to experimental physics, such as supersymmetric gauge theories (SUSY QFT) and strongly correlated systems, is very important for modern science. String theory, particularly the AdS/CFT correspondence, is a key tool for these studies. It allows us to develop methods to study and create gauge field theories and understand non-Lagrangian operators through supergravity solutions.
The Yang-Baxter deformation technique maps nonlinear transformations from supergravity solutions to gauge field theories using AdS/CFT. This non-linear transformation, based on hidden symmetries of supergravity equations, was initially limited to Abelian isometries. However, it has been extended to non-Abelian isometries. This generalization provides a way to find a new non-supersymmetric conformal manifold in gauge field theories.

We extend the notion of color superconductivity for d-dimension AdS spacetime to find the condition of Nc to give the general diquarks condensate in d-1 dimension boundary which only use the Einstein Maxwell gravity in d-dimension. We find the relation between Nc and number of dimension of AdS spacetime.

It is shown that the existing ambiguities in the theoretical in the
definitions of Higgs vacuum expectation value result in the PT-related ambiguities
of the electroweaek PT effects , which correlate with PT QCD variation
of running heavy quark masses scale-dependency The importance of taking these unfixed previously uncertainties in the theory predictions for the decays widths of Higgs boson to
heavy quark antiguark pairs is clarified

The current experimental data of New-Physics searches have excluded the simplest scenarios of the minimal supersymmetry (SUSY). At the same time, the Minimal Supersymmetric Standard model (MSSM) in general remains a possible candidate as the Standard Model extension. We propose a phenomenological scenario with nonstandard regime of softly broken SUSY-parameters ("regime of large A, mu"). For such a regime, radiative corrections to the dimension-six operators that inevitably arise at the loop level of effective Higgs potential decomposition become considerable. The Higgs alignment limit valid for the general Two-Higgs Doublet Model (THDM) with all possible CP-violating sources is investigated: it is shown that two different parametric scenarios, I and II, can be realized. The corresponding CP-violating effects are evaluated. It is found that the renormalization group improvement of radiative corrections refines predictions for the mass of the SM-like Higgs boson by about 2% for the Higgs alignment limit I and by about 9% for the Higgs alignment limit II.

The possibility of the lightest sterile neutrino with a mass of about a few keV as warm dark matter (DM) in the framework of the Minimal left-right symmetric model (MLRM) based on the SU(3)cSU(2)LSU(2)R*U(1) gauge group is considered. Only few parameters of the model are free which makes it rather predictable and unambiguous. We thoroughly consider a parametrization in the lepton sector and obtain a general form for mixing matrices and mixing parameters. Cosmological and astrophysical constraints on DM neutrino are analyzed. In the case of the mass of W_R of about 5 TeV, the model phenomenology consistent with current experimental data is considered.

Free and interacting fixed points of the renormalisation group play an important role in particle and statistical physics. High energy fixed points such as in asymptotic freedom or asymptotic safety are crucial for a fundamental definition
of quantum field theory. Low energy fixed points relate to (quantum) phase transitions and critical phenomena.

In this talk, I explain how and why weakly interacting fixed points arise in general 4d QFTs. This covers general theorems, necessary and sufficient conditions for existence, and explicit examples. In addition, I also review the last progress in calculation of beta functions, anomalous dimensions up to four loop in the gauge and three loop in the Yukawa and scalar couplings, and some implications of our results for conformal field theory and particle physics.

The study of the effective potential for non-renormalisable (super)symmetric models leads to recurrence relations for the leading singularities. These relations can be transformed into generalised renormalization-group (RG) equation which can be analyzed in detail. In some special cases this equation can be solved exactly.

Up to this date the process of hadronization is considered to be a “black box” as its soft nature does not allow to build a consistent theory. Instead, different models are used to describe the production of final-state hadrons, among which string models are considered to be the most successful.

There are some unresolved problems of the hadronization that existing models fail to prevail: the inability to use the same model to describe the fragmentation of light and heavy quarks, no angular momentum conservation, only simplified string dynamics and the use of initial conditions that do not satisfy the gauge of the string theory.

To overcome these challenges, a new model, called ATROPOS, was developed. It is based on the Area Decay Law that steers the fragmentation process, and the open relativistic string dynamics is derived from (modified) Nambu-Goto action. To take into account the masses of heavy quarks, model uses the apparatus, suggested by Barbashov and Nesterenko.

A real highlight of the study is the investigation of the ways to define the initial conditions that are used to calculate string movement. Interesting results are obtained by considering the restrictions imposed by Virasoro conditions and 4-momentum vector and angular momentum tensor conservation. It is shown, that a very non-trivial method to define initial state of the string must be used even for the simplest case of the zero-gluon string with free ends.

The first results of the hadronization simulation performed for e+e- events are presented and discussed. The influence of the string angular momentum on the hadron production is considered.

A new generalization of the Multipomeron exchange model (MEM) [1-3] for pp collisions is proposed, taking into account the effect of event-by-event string tension fluctuations [4]. It is shown that the new version of the MEM correctly reproduces the characteristic thermal behavior of $p_\mathrm{T}$ spectra in a wide energy range. In addition, the new generalization of the MEM improves the description of multiplicity distributions by replacing the Poisson distribution from one string with the discrete Gaussian distribution [5]. Calculations show that the new version of the MEM correctly reproduces the characteristic oscillating behavior of modified combinants in pp collisions over a wide energy range [5]. Simultaneously, the $p_\mathrm{T}$-multiplicity correlation functions are shown to be satisfactorily described together with the multiplicity-dependent $p_\mathrm{T}$ spectrum [6]. Possible applications of the new model for describing the relativisti heavy-ion collisions and opportunities for experiments at the NICA collider (Dubna) are discussed.

The authors acknowledge Saint-Petersburg State University for a research project 95413904.

1. Armesto, N.; Derkach, D.A.; Feofilov, G.A. p(t)-multiplicity correlations in a multi-Pomeron-exchange model with string collective effects. Phys. Atom. Nucl. 2008, 71, 2087–2095. https://doi.org/10.1134/S1063778808120090

2. Bodnia, E.; Derkach, D.; Feofilov, G.; Kovalenko, V.; Puchkov, A. Multi-pomeron exchange model for pp and $p\bar{p}$ collisions at ultra-high energy. PoS QFTHEP2013 2013, 60. https://doi.org/10.22323/1.183.0060

3. Kovalenko, V.; Feofilov, G.; Puchkov, A.; Valiev, F. Multipomeron Model with Collective Effects for High-Energy Hadron Collisions. Universe 2022, 8, 246. https://doi.org/10.3390/universe8040246

4. Bialas, A. Fluctuations of the string tension and transverse mass distribution. Phys. Lett. B. 1999, 466, 301–304. https://doi.org/10.1016/S0370-2693%2899%2901159-4

5. Vechernin, V.; Andronov, E.; Kovalenko, V.; Puchkov, A. Multiplicity Distributions and Modified Combinants in the Multipomeron Model of pp Interaction at High Energies. Universe 2024, 10, 56. https://doi.org/10.3390/universe10020056

6. Acharya, S. et al. Multiplicity dependence of charged-particle production in pp, p-Pb, Xe-Xe and Pb-Pb collisions at the LHC. Phys. Lett. B 2023, 138110 https://doi.org/10.1016/j.physletb.2023.138110

A.T. D’yachenko$^{1,2}$

$^{1}$ B.P. Konstantinov Petersburg Nuclear Physics Institute of National Research Center "Kurchatov Institute", Gatchina, Russia

$^{2}$ Emperor Alexander I Petersburg State Transport University, St. Petersburg, Russia

Based on the nonequilibrium hydrodynamic approach [1,2], double differential cross sections for the spectra of light fragments emitted in the FRAGM (ITEP) experiment [3,4] in collisions of carbon nuclei with a beryllium target at energies of 300 and 950 MeV/nucleon are described. To describe the fragment yield, the coalescence model [5,6] was used taking into account the Goldhaber factorization [7]

In the nonequilibrium hydrodynamic approach at high energies of colliding heavy ions, the Hubble law for the resulting fireball during its expansion was studied and in this approximation agreement with the results of calculations using the PHSD model [8] was obtained.

Taking the Hubble law as a basis, in the next approximation within the framework of hydrodynamics, the average vorticity was found and the polarization of the emitted particles in collisions of gold nuclei at an energy of GeV/nucleon was estimated. For the impact parameter fm, the polarization turned out to be about 5%, which is in agreement with the experimental data of the STAR collaboration for hyperons and calculations using the PHSD model [8]. This may be of interest for future experiments at the NICA collider

1. A.T. D’yachenko, I.A. Mitropolsky, Phys. Atom. Nucl. 85, 1053 (2022).
2. A.T.D’yachenko, Phys.Atom. Nucl. 87,. 125 (2024).
3. A.A. Kulikovskaya et al., Phys.Atom.Nucl. 85, 466 (2022).
4. В.M. Abramov et al. Phys.Atom.Nucl. 81, 330 (2018).
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6. A.T.D’yachenko, I.A. Mitropolsky, Bull. Russ. Acad. Sci.: Physics 81, 1521 (2017).
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Experimental studies in the recent decades have provided strong evidence for the formation of hot and dense nuclear matter in heavy-ion collisions. Such matter is predicted by Quantum Chromodynamics (QCD) to be a quark-gluon plasma (QGP) consisting of deconfined quarks and gluons. Direct photons, which are not originating from hadron decays, are one of the key experimental observables of QGP. At low transverse momenta ($p_{\mathrm{T}}$), an exponential spectrum of thermal direct photons ($p_{\rm{T}}\le 2$ GeV/$c$) captures features of space-time evolution of the QGP expansion and the hadronic gas. Additionally, the thermal direct photon spectrum could be expanded down to lower $p_{\mathrm{T}}$ using correlations of soft photons. Hanbury Brown and Twiss (HBT) correlation of direct photons can shed light on the space-time properties of QGP. ALICE is capable to measure photons in wide range of $p_{\mathrm{T}}$, exploiting detectors the tracking system for measurements of photon conversion into $e^+e^-$ pairs. High-$p_{\mathrm{T}}$ photons are measured with electromagnetic calorimeters EMCal and PHOS. In this talk, the direct photon production and HBT correlations in Pb--Pb collisions at $\sqrt{s_{NN}} = 5.02$ TeV with ALICE are reported.

Search for signatures of phase transitions and determination of phase diagram of nuclear matter created in A+A collisions are in the heart of the heavy ion programs performed present at RHIC, LHC and future experiments at NICA and FAIR.
In the paper the hypothesis of the self-similarity of hadron production in relativistic heavy-ion collisions to search for the phase transition in nuclear matter is discussed. Using the established features of z-scaling is suggested to reveal the signatures of new physics in the cumulative region. Selection of the cumulative events is assumed to enrich data sample by a new type of collisions characterized by higher energy density and more compressed matter. We expect that this would allow finding clearer signatures of phase transition, location of a critical point and studying extreme conditions in heavy ion collisions. The change in the parameters of the theory (a specific heat and fractal dimensions) near the critical point is considered a signature of new physics. The results of data analysis of cumulative production in p+A and A+A collisions in collider and fixed target mode are discussed.

1. M.Tokarev and I.Zborovský, Phys. Part. Nucl. Lett., 7 (2010) 160.
2. M.Tokarev, I.Zborovský and A.A.Aparin, Phys. Part. Nucl. Lett., 12 (2015) 324.
3. M.Tokarev, A.Kechechyan, and I.Zborovský, Nucl. Phys., A 993 (2020) 121646).
4. M.Tokarev and I.Zborovský, Nucl. Phys., A1025 (2022) 122492.

Phase diagram of two color and three color QCD are reviewed. The dualities of QCD phase diagram are discussed in both two and three color cases. It has been shown that the phase diagram of two color QCD is quite helpful and it has a lot of common features with three color one, and predictions recently made in two color QCD was shown to hold qualitatively in real three color QCD. Showing that two color QCD is indeed great lab to study dense quark matter. The dualities has been shown in two color QCD. Duality between chiral symmetry breaking and charged pion condensation phenomena has been demonstrated from first principles in QCD itself. Also there will be discussed color superconductivity phenomenon and the influence of chiral imbalance on its properties.

Despite the fact that the thermodynamic potential in three color case ($N_c=3$) does not have properties of all three dualities found in the two-color case, it turned out that the phase portrait qualitatively contains these dualities.

This work focuses on exploring the potential of machine learning methods in relativistic nuclear physics to differentiate between various physical theories, and consequently, gain a deeper understanding of the underlying physical processes in ultra-high-energy nuclear collisions.
Recent findings from modeling p+p and AA interactions within the color string fusion framework suggest that it may be possible to describe the experimental azimuthal asymmetry event-by-event in a unified way across different colliding systems. This description becomes possible by considering two mechanisms of string interactions: 1) changes in the strength of the color field in the area where strings overlap in the transverse plane, and 2) Lorentz boosts applied to particles resulting from string motion due to mutual attraction. We demonstrate that it is possible to train machine learning algorithms using pT-φ distributions from event-by-event data in order to distinguish between different sources of collective behaviour.

This work was supported by the Russian Science Foundation under grant no.23-72-01061.

The centrality that describes the initial collision geometry is crucial for interpreting experimental data on heavy ion collisions.
We present the procedures of centrality determination for the Baryonic Matter at Nuclotron (BM@N) experiment based on the multiplicities of produced particles. The validity of the procedures is assessed using the experimental data for Xe+Cs(I) collisions at beam kinetic energy of 3.8 A GeV.

The upgraded near neutrino detector[1,2,3] of the T2K experiment[4] is briefly described. The central part is the 3D scintillator fine-grained detector (SuperFGD). The detector comprised of about 2 million 1 × 1 × 1 cm3 plastic scintillator cubes with three orthogonal holes for wavelength shifting fiber readout[2,5]. It will be used as an active neutrino target to detect charged particles and photons. A combination of SuperFGD with the other subdetector systems in the ND280 detector provides a possibility to detect more neutrino events (due to an additional active target), as well as to increase the accuracy of the neutrino events reconstruction[3]. In this work, the results of Monte Carlo simulation of the interactions of electron and muon neutrinos in the updated ND280 complex are presented. The efficiency of matching tracks between SuperFGD and other subdetectors of the upgraded ND280 will be discussed.

Hyper-Kamiokande is a new generation of 260 kiloton water Cherenkov detector, construction of which began in 2020. One of the main goals is to search for CP symmetry violation in neutrino oscillations. Hyper-Kamiokande is divided into internal and outer detectors, which are equipped with photomultiplier tubes (PMT). The outer detector (OD) is used as a veto system for incoming charged particles, mainly muons. In OD, Cherenkov radiation is detected by photomultipliers with a diameter of 8 cm and wavelenght-shifting (WLS) plates, which cover the “dead” space between the photomultipliers and thereby increase the light collection area of OD and increase the efficiency of detecting background events. In total, it is planned to use about 3600 photomultipliers in combination with WLS plates in the Hyper-Kamiokande outer detector. Light from Cherenkov radiation will hit the plates, be absorbed and then re-emitted in accordance with the relationship between the emission and absorption spectra of the material used. The report will present the results of a study of parameters of WLS plates and a method for quick tests and control their quality.

Currently, one of the most significant areas of research in physics is the search for neutrinoless double beta decay. To conduct such studies, it is necessary to minimize the level of the radioactive background of the experiment. The selection of the purest structural materials is necessary, since the achieved background level determines the final sensitivity of the experiment to the studied physical processes. This is achieved through various methods, including placing installations in underground laboratories, carefully selecting structural materials, and using active background suppression techniques. However, the new generation of experiments require an even lower level of natural radioactive background. Both the detector itself and its surrounding shield elements contain background sources that are unavoidable. Therefore, it is not only important to look for new materials with lower backgrounds, but also to ensure that there is no radioactive contamination during the production and processing of parts. At present, 3D printing technology has become widely used. The use of this technology can avoid the need for mechanical processing of manufactured parts, preventing potential additional contamination during the manufacturing process, reducing its duration, and reducing the number of steps required for final cleaning before installing the parts. 3D printing allows for the creation of complex structural elements with acceptable mechanical strength using a small
amount of material, and manufacturing parts in a shorter time.

We have studied the possibility of using 3D printing to create structural elements of low-background detectors and low-background shields. The materials used for 3D printing were studied using low-background semiconductor gamma-ray spectrometers at the Baksan Neutrino Observatory of the INR RAS in order to measure the activity of radioactive impurities in these materials. These measurements made it possible to select the purest samples of filaments for 3D printing, which were subsequently used in the development and printing of the body of the test scintillation detector.

Test calibration measurements were carried out using a scintillation detector with a body printed on a 3D printer in order to verify the possibility of using 3D printing to create structural elements of detectors. We have printed the body of a scintillation detector with a volume of 100 cm3. A scintillation detector was manufactured using a LAB-based scintillator with the additives PPO (2 g/L) and Bis-MSB (0.02 g/L), which was filled into a printed case. The volume of the detector was viewed using the PMT-97. To verify the functionality of the experimental setup, a series of measurements were carried out using calibration sources $^{137}$Cs and $^{60}$Co. The background spectrum was collected over a period of 16 hours at the Laboratory Building of the BNO INR RAS. The results obtained confirmed the feasibility of using 3D printing for manufacturing structural elements of detectors. In the next stage, to avoid possible contamination of the samples during printing by $^{222}$Rn daughter products or other radioactive isotopes that may be present in the air, we plan to place the printer in a dust-free area of the low-background, deep-laying laboratory at the BNO INR RAS. It is planned to additionally place it in a special protective casing surrounding the 3D printer, in which a nitrogen (or argon) atmosphere will be created.

This study was supported within the State contract of the Ministry of Science and Higher Education of the Russian Federation no. FZZR-2022-0004.

The use of large-area photomultipliers is reasonable in large-volume liquid-scintillation neutrino detectors, such as JUNO or the planned Baksan Large Neutrino Telescope. There are currently two models of 20-inch photomultipliers on the market, the dynode-PMTs Hamamatsu R12680 and the NNVT MCP-PMTs (microchannel plate PMTs), both are used in JUNO. However, despite some advantages of the NNVT MCP-PMT, there is a problem of determining their single-photoelectron response, which entails the problem of determining the number of photoelectrons and, therefore, the energy of the particles. In this work, we have studied the single-photoelectron response of the NNVT MCP-PMT and some of its other characteristics, and compared them with the characteristics of the Hamamatsu R12860.

Liquid scintillators have always been an important part of many experiments in
neutrino physics. The liquid scintillator based on linear alkylbenzene (LAB) is
used in a prototype of Baksan Large Neutrino Telescope, which is proposed to be
constructed at the Baksan Neutrino Observatory. The main disadvantage of liquid
scintillator is the non-linear response to highly ionizing radiation, called ionization quenching. The response of the LAB-based scintillator was measured in the energy range of gamma-quanta from 60 keV to 1.3 MeV and the Birks parameter was obtained. The 14C content of a LAB-based scintillator has been measured using the prototype of Baksan Large Neutrino Telescope with the scintillator mass of 0.5 tons. The 14C/12C ratio has been obtained.

The availability of the necessary infrastructure is a prerequisite for the proper functioning of the detector, the article describes a magnetic field compensation system and a liquid scintillator purification system for a 5-ton prototype of the Baksan large neutrino telescope. Detectors based on liquid scintillators play an important role in experiments in neutrino physics and particle astrophysics. Currently, a liquid scintillator based on linear alkylbenzene (LAB) with the addition of PPO (2,5-diphenyloxazole) and bis-MSB (1,4-bis(2-methylstiryl)benzene) is actively used in large-scale neutrino experiments. High optical characteristics of the scintillator and a low radioactive background are necessary for the effective operation of the detector. The main methods of cleaning liquid scintillators are:
1. Chromatographic purification on columns filled with aluminum oxide (Al2O3), which removes organic and radioactive impurities and increases transparency
2. Water extraction to remove radioactive impurities
3. Vacuum molecular distillation
Photomultiplier tubes, especially large-sized PMTs used in the project, are sensitive to a magnetic field. The influence of the magnetic field has a negative effect on the resolution of the photomultiplier tubes, and it also affects the jitter in the PMT, which ultimately affects the accuracy of localization of the scintillation flash in the target volume. In this case, it is necessary to use a magnetic field compensation system

The Jiangmen Underground Neutrino Observatory (JUNO) experiment is a new generation neutrino project. Its main and ultimate goal is to determine the neutrino mass ordering. To achieve this fundamental milestone, the precise reactor neutrino spectroscopy based on the Inverse Beta Decay reaction will be applied. The approach implies detailed knowledge of all relevant backgrounds in the liquid scintillator target of the detector. One significant background are (α, n) reactions, which occur on 13C nuclei and are possible due to the presence of residual radio-impurities, mainly, 238U, 232Th and 210Pb. This work describes the simulation of this background, performed using open source Geant4-based software called SaG4n, a new event generator and the dedicated JUNO detector response simulation package. All stages of the reaction were considered, including, in particular, the α particle propagation in the medium before the interaction and emission of a neutron and de-excitation particles from the excited states of the final nucleus. The total and partial (α, n) background event rates and the respective shapes of the energy spectra have been obtained within the expected radioactivity concentration. The simulation pipeline and its outcomes are relevant for other neutrino experiments using organic liquid scintillator and may be useful for dark matter search projects.

This work is supported in the framework of the State project “Science” by the Ministry of Science and Higher Education of the Russian Federation under the contract 075-15-2024-541.

A new Highly Granular Neutron Detector (HGND) is being developed and constructed in order to identify neutrons and to measure their energies from nucleus-nucleus collisions at the BM@N experiment (JINR). The HGND consists of alternating layers of copper absorber plates and matrices of scintillation cells with individual light readout by silicon photomultipliers. The HGND will be used in the fixed target BM@N experiment in heavy-ion collisions with energies up to 4 GeV per nucleon.
The ratios of direct and elliptic azimuthal neutron flow to the corresponding proton flow, which can be measured with the magnetic spectrometer of the BM@N facility, should be sensitive, as shown in a number of models, to the symmetry energy in the equation of state (EoS) of high dense nuclear matter. The performance studies based on the results of simulations of the new HGND detector at the BM@N experiment will be presented. The current status of the HGND construction will be discussed.

A modular SrI2(Eu) scintillation ultra-low energy threshold neutrino detector is being developed in INR RAS to research low energy neutrinos produced in radioactive isotope decays and also reactor neutrinos. Proposed layer structure of the detector allows to easily scale it depending on the task. Each layer will consist of 16 modules, each comprising 4 scintillation crystals. Readout of each crystal is done by a SiPM matrix. In this work, performance of SrI2(Eu) scintillation detectors will be discussed. The light yield of SrI2(Eu) scintillator can reach up to 120 p.e./keV. SiPMs with high photon detection efficiency (PDE) of around 50% can be used to lower the threshold down to ~100 eV. SrI2(Eu) emission spectrum aligns well with SiPM maximum PDE. It will be shown that Dark Current Rate (DCR), which is the main disadvantage of utilizing SiPMs for low threshold measurements, is suppressed at temperatures below -60°C. DCR of several SiPM matrixes was tested in a broad temperature range for various operating voltages. The measurements show satisfactory light yield of tested SrI2(Eu) scintillation detector prototypes. Preliminary results of scintillation detectors confirm the ability to detect recoil electrons with energy below 1 keV. A developed coincidence scheme and single electron counting regime should allow to decrease noise rate and to detect events with the discussed threshold of 100 eV.

The fluctuation of the number of charged particles in a given rapidity interval of observation was studied. Analytical expressions and the Monte Carlo modeling in the framework of a quark-gluon string model were used to calculate scaled and robust variance of the multiplicity in the case with string fusion and without it. The used distribution of primary strings in the transverse plane is consistent with the Regge approach. The string fusion effects were taken into account by implementing of a lattice (grid) in the impact parameter plane.
The value of the scaled and robust variance of the multiplicity for pp collisions is calculated at three initial energies: 0.9, 2.76 and 7 TeV, both with and without taking into account the processes of string fusion. The results were compared with the data obtained by ALICE collaborations at CERN. The results of these analytical calculations coincide with the results of MC simulations, this testifies to the correctness of the MC algorithm used. It is shown that for pp collisions at LHC energies, the fluctuations of the particle number from a given string cluster are, due to the presence of short-range correlations between particles, significantly larger than the Poisson ones.

The authors acknowledge Saint-Petersburg State University for a research project 95413904

This work focuses on the calculation of quark counting rules for the inclusive production of pions at large transverse momenta in the cumulative region—a kinematic domain forbidden for single nucleon-nucleon interactions. This region, which cannot be accessed through single nucleon-nucleon interactions, becomes relevant in nuclear collisions and can be observed using the MPD and SPD detectors at the NICA complex. Unlike high-energy colliders like RHIC and LHC, where this phenomenon cannot be studied due to kinematic limitations, the intermediate energy collisions at NICA provide a distinctive opportunity to investigate these cumulative effects in detail.

The concept of the flucton, a cluster of cold, dense quark-gluon matter with high baryon density, plays a central role in this context. From a modern perspective, fluctons are seen as temporary, highly localized concentrations of quarks and gluons within the colliding nuclei, and their presence enables the production of cumulative particles during the collision. If a flucton is present during nucleon collisions, it can trigger the production of particles that exhibit unusual kinematic properties, including those with large transverse momenta at mid-rapidities.

Building on the earlier work of V. V. Vechernin and M. A. Braun [1-4], who developed a microscopic quark-parton model for particle production in the fragmentation region of one of the colliding nuclei, we extend this framework to the new kinematic region characterized by high transverse momentum. In this extended region, we observe a shift in the proton-to-pion yield ratio when compared to cumulative particle production in the traditional fragmentation region. This is largely due to the different underlying mechanisms of particle formation: while cumulative protons are predominantly formed through the coherent recombination of three quarks from a flucton, cumulative pions are primarily produced via the fragmentation of a single quark [3, 4, 9]. We compare the obtained theoretical results with the results of our preliminary estimates of particle yields in this region based on a more phenomenological approach [5-7].

Moreover, our work reveals the potential for studying flucton-flucton interactions—a rare and intriguing process—in the new cumulative region at mid-rapidities. Unlike the fragmentation region, where such interactions are impossible to observe, this region opens up the possibility for detailed experimental investigation. Notably, this process can be explored in detail using dd (deuteron-deuteron) collisions at the NICA SPD, where both deuterons may exist as flucton states at the moment of collision. In this scenario, the absence of additional nucleon-nucleon interactions reduces background, simplifying the detection of cumulative particles in correlation with those originating from flucton fragmentation [8]. The higher collision rate at SPD compared to MPD also enhances the likelihood of observing rare cumulative events, making SPD a particularly valuable tool for these studies.

The work was supported by the Russian Science Foundation grant 23-12-00042.

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4. V.V. Vechernin, AIP Conf. Proc. 1707, 060020 (2016).
5. V.V. Vechernin, Phys. Part. Nuclei 52, 604-608 (2021).
6. V.I. Zherebchevsky, V.P. Kondratiev, V.V. Vechernin, S.N. Igolkin,
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7. V.V. Vechernin, Phys. Part. Nuclei 53, 433-440 (2022).
8. V. Vechernin, S. Belokurova, S. Yurchenko, Symmetry 16, 79 (2024).
9. V.V. Vechernin, Phys. Part. Nuclei 54, 528-535 (2023).

Inverse gluon emission in the dilepton production process in hadron collisions for Large Hadron Collider (LHC) experimental program aimed at exploring the Drell-Yan process are estimated in details. Numerical analysis of inverse emission effects to observable quantities (cross sections and forward-backward asymmetry) is performed in a wide kinematical region including the CMS LHC experiment in Run3/HL regime which corresponds to ultra-high energies and dilepton invariant masses. Effective technics for analysis of different radiative contributions influence on forward-backward asymmetry using two additive relative corrections is suggested.

The effects of polarization transfer from the initial electron to the bremsstrahlung photon in the electron–nucleus scattering (Bethe-Heitler process) are considered. The calculation is done without the assumption of smallness of the electron mass nor the limitation to small photon emission angles. Detailed comparison with a series of preceding papers is done. The results are applicable to the modelling of the polarized cross sections at low energies and beyond, even at a few MeV.

The study of the associated production of $J/\psi$-mesons and
photons is very impotent to verify perturbative quantum
chromodynamics, factorization approaches, heavy quark to heavy
quarkonium hadronization models and to extracting the Parton
Distribution Function (PDF) of gluon in a proton from experimental
data. In this paper, we study the associated production of
$J/\psi$-mesons and photons at the energies of the Large Hadron
Collider using the Parton Reggeization Approach (PRA) [1], which is
based on Lipatov's effective field theory [2] and the modified
Kimber-Martin-Ryskin model for unintegrated PDFs [3, 4]. We use two
different heavy-quark to heavy quarkonium hadronization models: the
non-relativistic quantum chromodynamics (NRQCD) [5] and the improved
color evaporation model (ICEM) [6].

We have found that the PRA based predictions for production cross
sections are higher than next-to-leading order collinear parton
model results. We have shown that contributions of the direct
production processes via the color-octet intermediate states in the
NRQCD are suppressed relatively to the process via the color-singlet
intermediate state, so the Color Singlet Model (CSM) can be used for
predictions at the $p_{TJ/\psi}<40~\text{GeV}$. The long distance
matrix elements of the NRQCD and ICEM parameter $F_\psi$ in the
calculations are taken as they have been obtained to describe
experimental data of the $J/\psi$-meson prompt production at the LHC
energies.

We have predicted various differential cross-sections for associated
production of $J/\psi$-mesons and photons in the PRA at the
center-of-mass energy $\sqrt{s} = 13$ TeV in the central rapidity
region. We have obtained that the PRA using the CSM cross-sections
strongly overestimate the results obtained in the PRA using the ICEM
and this difference increases as more as the cutoff on the photon
transverse momentum $p_T$ becomes larger. The results of this study
indicate that there are big difference between the ICEM based and
the NRQCD based predictions for the associated $J/\psi+\gamma$
production that can be used for discrimination heavy quark to heavy
quarkonium hadronization models.

[1] M.A. Nefedov, V.A. Saleev, and A.V. Shipilova. Dijet azimuthal decorrelations at the LHC in the parton Reggeization approach. Physical Review D, 87(9):094030, 2013.

[2] L.N. Lipatov. Gauge invariant effective action for high energy processes in QCD. Nuclear Physics B, 452(1-2):369–397, 1995.

[3] M.A. Kimber, A.D. Martin, and M.G. Ryskin. Unintegrated parton distributions. Physical Review D, 63(11):114027, 2001.

[4] M.A. Nefedov and V.A. Saleev. High-energy factorization for the Drell-Yan process in $pp$ and $p\bar{p}$ collisions with new unintegrated PDFs. Physical Review D, 102(11):114018, 2020.

[5] G.T. Bodwin, E. Braaten, and G.P. Lepage. Rigorous QCD analysis of inclusive annihilation and production of heavy quarkonium. Physical Review D, 51(3):1125, 1995.

[6] Y.Q. Ma, R. Vogt. Quarkonium production in an improved color evaporation model. Physical Review D, 94(11), 114029, 2016.

Prompt heavy quarkonium production is well described within the collinear parton model in the next-to-leading order of perturbaive QCD at kinematical region of $p_T^{} \gg M$ where $M$ is a mass of a quarkonium state. But the region of small $p_T^{}$ is still being researched and the factorisation approach which is valid here is TMD-factorisation (transverse-momentum dependent). We studied $J/\psi$ production in collision of protons at $\sqrt{s} = 200, 27$ and $19.4$ GeV. Certainly, we used Nonrelativistic QCD (NRQCD) as a standard hadronisation model for charmonium production, and we extracted nonperturbative matrix elements for octet color states of the NRQCD from a set of experimental data on prompt $J/\psi$ production because color singlet model can't be considered as sufficient for experimental data description.

The TMD approach is a general factorisation model for $p_T^{} \ll M$ region [1]. One of the realisations of the TMD-factorisation is a so called Soft Gluon Resummation approach [2] where soft gluon emission by partons is considered, evolution of the TMD parton distribution functions is controlled by the Collins -- Soper equations [3] though the TMD distribution is partly reduced to the collinear one. We perform our study at the LO$+$LL approximation for now. We describe data from PHENIX Collaboration at $\sqrt{s} = 200$ GeV and from NA3 Collaboration at $\sqrt{s} = 19.4$ GeV and do predictions for future SPD NICA experiments at $\sqrt{s} = 27$ GeV. We considered both gluons and quarks as initial partons, we also estimated a contribution of $P$-wave charmonium production and calculated polarised $J/\psi$ production as an angular coefficient $\lambda$. The Inverse-Error Weighting Scheme [4] is used as an approach for matching of collinear and TMD factorisations.

References:

[1] J. C. Collins. Foundations of Perturbative QCD, Cambridge Univ. Press, Cambridge (2011).

[2] J. Bor and D. Boer. TMD evolution study of the $\cos 2\phi$ azimuthal asymmetry in unpolarized $J/\psi$ production at EIC, Phys. Rev. D 106, 1 (2022).

[3] J. C. Collins, D. E. Soper, and G. Sterman. Transverse momentum distribution in Drell-Yan pair and $W$ and $Z$ boson production, Nuclear Physics B 250 (1-4), 199--224 (1985).

[4] M. G. Echevarria, T. Kasemets, J.-P. Lansberg, C. Pisano, A. Signori. Matching factorization theorems with an inverse-error weighting, Phys. Lett. B 781, 161--168 (2018).

The production of Mueller-Navelet dijets is studied within the framework of the
High-Energy Factorization approach [1,2,3]. Such processes are considered to be
sensitive to the effects of BFKL resummation [4]. In the Ref.[5] it was shown
that experimental data for dijets with large rapidity gaps can't be described
using NLO DGLAP based Monte-Carlo generators. In the study, we predict cross
sections for the production of dijets using the Reggeon-Reggeon-Particle-Particle effective vertices obtained within the formalism of the L.N. Lipatov's Effective Field Theory [6]. Calculations are performed using two different unintegrated PDF sets [7,8].

[1] J. Collins and R. Ellis. Nucl.Phys.B 360 (1991) 3-30;

[2] S. Catani and F. Hautmann. Nucl.Phys.B 427 (1994) 475-524;

[3] L.V. Gribov, E.M. Levin, M.G. Ryskin. Phys.Rept. 100 (1983) 1-150;

[4] A. Mueller and H. Navelet. Nucl.Phys.B 282 (1987) 727-744;

[5] CMS Collaboration. JHEP 03 (2022) 189;

[6] L.N. Lipatov. Nucl.Phys.B 452 (1995) 369-400;

[7] M. Nefedov and V. Saleev. Phys.Rev.D 102 (2020) 114018;

[8] J. Blumlein. DESY-95-121.

Neutrino propagation in Galactic and extragalactic magnetic fields is considered. We extend an approach developed in [1] to describe neutrino flavour and spin oscillations on astrophysical baselines using wave packets. The evolution equations for the neutrino wave packets in uniform and non-uniform magnetic fields are derived. The analytical expressions for neutrino flavour and spin oscillations probabilities accounting for damping due to the wave packet separation are obtained for the case of a uniform magnetic field. It is shown that terms in the flavour oscillations probabilities that depend on the magnetic field strength are characterized by two coherence lengths. One of the coherence lengths coincides with the coherence length for neutrino oscillations in vacuum, while the second one is proportional to the cube of the average neutrino momentum $p_0^3$. The probabilities of flavour and spin oscillations are calculated numerically for neutrino interacting with the non-uniform Galactic magnetic field. It is shown that oscillations on certain frequencies are suppressed on the Galactic scale due to the neutrino wave packets separation. The flavour compositions of high-energy neutrino flux coming from the Galactic centre and ultra-high energy neutrinos from an extragalactic source are calculated accounting for neutrino interaction with the magnetic field and decoherence due to the wave packet separation. It is shown that for neutrino magnetic moments $\sim 10^{-13} \mu_B$ and larger these flavour compositions significantly differ from ones predicted by the vacuum neutrino oscillations scenario.

Based on:

1) A.Popov, A.Studenikin, "High-energy neutrinos flavour composition as a probe of neutrino magnetic moments", arXiv: https://arxiv.org/abs/2404.02027.

2) A.Popov, A.Studenikin, Manifestations of nonzero Majorana CP-violating phases in oscillations of supernova neutrinos, Phys.Rev.D 103 (2021) 11, 115027.

3) A.Popov, A.Studenikin, Neutrino eigenstates and flavour, spin and spin-flavour oscillations in a constant magnetic field, Eur.Phys.J.C 79 (2019) 2, 144.

Nowadays, research in the field of extreme states of matter is actively developing, e.g. study of quark-gluon plasma. In this regard, the comprehensive application of various models that describe the phenomena occurring with matter, for example, in relativistic collisions of heavy ions at the accelerators, is also developing. New methods of studying extreme conditions are being built, and methods of working with them are being improved. One of these methods is the investigated study of nuclear collision using Monte Carlo generators.

In reality, accelerators and detector complexes serve as a platform for such research. In our work, we will focus mainly on the results obtained by the CMS [1] collaboration working at the Large Hadron Collider. Conducting research since 2010, the CMS collaboration has already published more than two hundreds scientific articles [2] on heavy ion physics. These articles discuss in detail various methods for calculating azimuthal fluxes of charged particles: the method of the true reaction plane, the second and fourth order cumulants, two-particle correlations, etc [3,4]. This work will be devoted to the study of these methods and their implementation in the Monte Carlo generator HYDJET++ [5].

HYDJET++ is a Monte Carlo model for generating relativistic collisions of heavy ions. It includes a combination of two independent components: a soft hydrodynamic part for low-energy particles and a hard part for jets and hadrons, taking into account the effect of their quenching due to energy losses in a dense matter. Initially, the azimuthal flows of charged particles in the HYDJET++ generator are calculated using the true reaction plane method [6]. In the current work, we will demonstrate the results of integrating another methods into the HYDJET++ model.

The work considers methods for calculating azimuthal flows – elliptical v2 and triangular v3 – in collisions of lead and xenon ions. The reaction plane method involves finding the angle of the reaction plane and calculating harmonics relative to this angle. The cumulant method, accordingly, implies the calculation of cumulants that take into account correlations between particles. With the help of these methods, the calculation of flows is carried out, and the results are compared with those similar in the work of the CMS collaboration [3,4].

As a result of the work, the generation of relativistic collisions of lead ions at an energy of √sNN = 5.36 TeV per nucleon pair in c.m.s. and xenon with an energy of √sNN = 5.44 TeV per nucleon pair in c.m.s. Elliptical v2 and triangular v3 flows were calculated using various methods. The methods were analyzed and the obtained results were compared with the results of the CMS experiment [3,4]. This work will allow us to adjust the generator model in the future and identify areas in which the model does not perform well enough and future developing.

1. S. Chatrchyan et al. (CMS Collaboration). The CMS experiment at the CERN LHC // J. Instrum. 2008. No. 3, S08004.
2. CMS Collaboration. CMS heavy-ion physics publications http://cms-results.web.cern.ch/cms-results/public-results/publications/HIN/
3. S. Pandey, B. K. Singh. Anisotropic flow and correlations between azimuthal anisotropy Fourier harmonics in Xe–Xe collisions at √sNN = 5.44 TeV under HYDJET++ framework // Journal of Physics G: Nuclear and Particle Physics,2022 // arXiv:2107.01880. 2021.
4. S. Pandey, B.K. Singh. Transverse momentum spectra and suppression of charged hadrons in deformed Xe–Xe collisions at √sNN = 5.44 TeV using HYDJET++ model // arXiv:2210.08527. 2022.
5. I. P. Lokhtin, L. V. Malinina, S. V. Petrushanko, A. M. Snigirev, I. Arsene, K. Tywoniuk. Heavy ion event generator HYDJET++ (HYDrodynamics plus JETs) // Comput. Phys. Commun. 2009. V. 180, 779.
6. Д. А. Мягков, С. В. Петрушанко. Эллиптический и триангулярный потоки заряженных частиц в релятивистских столкновениях ядер Xe и Pb в модели HYDJET++ и эксперименте CMS (LHC) // Учен. зап. физ. фак-та Моск. ун-та. 2023. № 3. 2330205.

Anisotropic flow measurements of produced particles in relativistic heavy-ion collisions play an essential role in the studies of transport properties of the strongly interacting matter. In this work we provide the results of the most comprehensive systematic study of the beam energy dependence of anisotropic flow based on existing data and discuss them using different scaling relations for azimuthal anisotropy.

Hadronic matter in heavy-ion collisions can reach extreme energy densities and undergo a phase transition into quark-gluon plasma (QGP) consisting of asymptotically free partons. One of the main ways to investigate QGP’s properties is to measure the azimuthal particle anisotropy in momentum space. This anisotropy can be characterized by the elliptic flow ($v_2$).

The elliptic flow for charged hadrons was measured by PHENIX experiment at RHIC in small collision systems (p/d$/^3$He+Au). In the most central collisions, azimuthal anisotropy can be described by relativistic hydrodynamics, as in heavy-ion collisions. However, $v_2$ of charged hadrons in more peripheral collisions cannot be interpreted only as flow, but has significant nonflow contribution, which also depends on transverse momentum ($p_T$). Since the production of $\pi^0$ mesons can be measured up to high values of $p_T$, the measurement of the $v_2$ values for $\pi^0$ in $^3$He+Au collisions is considered unique tool to study the interplay between flow and nonflow effects in small systems.

The second part of this report is devoted to the measurement of $v_2$ values for $\pi^0$ mesons in U+U collision system – the largest system at RHIC. Since the $^{238}$U nucleus is highly deformed, the study of collisions of uranium nuclei is especially interesting from the point of view of studying jet-quenching effect. In heavy-ion collisions nonzero values of $v_2$ at high $p_T$ can be associated with partonic energy loss. This makes the elliptic flow of $\pi^0$ meson, which is measurable up to high $p_T$, effective tool to study jet-quenching effect in U+U collisions.

Thus, the current report is dedicated to the measurement of $\pi^0$ mesons elliptic flow in $^3$He+Au and U+U collisions at $\sqrt{s_{NN}}$=200 GeV and $\sqrt{s_{NN}}$=193 GeV, respectively, as a function of transverse momentum and centrality.

The report can be considered as a prototype of the research planned in the MPD experiment of the megaproject NICA.

We acknowledge support from Russian Ministry of Education and Science. State assignment for fundamental research (code FSEG-2024-0033).

The research on K(892) meson production can lead to a new discoveries in properties of exotic state of matter called quark-gluon plasma (QGP) in which quarks and gluons are deconfined. Strangeness enhancement is one of the main observables of QGP which can be measured by studying the production of particles containing strange quark(s). K(892) meson is one of such particles. Production of K(892) can be described by it’s invariant $p_T$ spectra. Comparison of production of K(892) in heavy and in p+p collision systems can be shown by nuclear modification factors. Since QGP isn’t formed in p+p collisions at $\sqrt{s_{NN}} = 200$ GeV strangeness enhancement can be observed through the nuclear modification factors.

Current report is dedicated to measurements of K*(892) mesons invariant $p_T$ spectra and nuclear modification factors as functions of transverse momentum and centrality in Au+Au collision system at $\sqrt{s_{NN}}= 200$ GeV.
The report can be considered as a prototype of the research planned in the MPD experiment of the megaproject NICA.

We acknowledge support from Russian Ministry of Education and Science. State assignment for fundamental research (code FSEG-2024-0033).

Measurement of properties of short-lived resonances produced in heavy-ion collisions plays an important role in study of the hot and dense medium produced in such collisions. Due to short lifetimes of resonances a significant part of them decays in the fireball. This makes resonances a unique tool for studying the evolution of the colliding system and related phenomena: excessive yield of baryons at intermediate momentum, flavor dependence of the parton energy loss, enhanced strangeness production, rescattering and regeneration in the hadron gas and others.
The study of resonance production in heavy ion collisions is an important part of the physical program of the MPD experiment at NICA. We present results of feasibility studies for measurement of φ(1020), ρ(770) and K*(892) mesons production in Bi + Bi collisions at √sNN = 9.2 GeV using the MPD detector at NICA collider. Results are obtained using full-scale Monte Carlo simulations of heavy-ion collisions and the experimental setup.
We acknowledge support from the Russian Ministry of Education and Science, state assignment for fundamental research (code FSEG-2024-0033).

Direct photons produced in electromagnetic processes in heavy ion collisions do not interact with other particles in the collision zone. Analysis of direct photon anisotropic flow could provide additional information on the conditions at the production time and on the development of collective flow. Direct photon flow is extracted based on flow and spectra of inclusive photons and of neutral pions, the main source of decay photons. Moreover, results for neutral pion spectra and flow are interesting themselves as they allow to constrain properties of hot and dense nuclear matter thanks to the robust particle identification and wide coverage in transverse momentum.

We present the performance for measurement of anisotropic flow for inclusive photon and neutral pion with the MPD experiment.

The BM@N (Baryonic Matter at Nuclotron) is a fixed-target detector for relativistic nuclear collisions at the NICA accelerator complex. The focus of the BM@N physics program is the study of the production of hadrons and light (hyper)nuclei in nucleus-nucleus interactions with energies up to 4A GeV. In this talk we present recent results on the production of protons, deuterons, and tritons in centrality selected argon-nucleus collisions at 3.2A GeV. Rapidity and transverse momentum distributions of p, d, t over a large phase space region will be shown. System size dependence of particle yields and ratios in Ar+A (A = C, Al, Cu, Sn, Pb) collisions will be discussed and tested against model predictions.

Heavy ion collision at the energies of several A GeV is the only way to produce in laboratory hot and dense matter existing in massive astrophysical objects such as neutron stars, binary stellar collisions etc. In 2023 Baryonic Matter at Nuclotron (BM@N) experiment collected the first physical data for Xe+CsI collisions at $E_{kin} = 3.8A$ GeV. Studying the observables from heavy ion collisions can shed light on the properties of the matter created and establish its Equation of State (EOS). Collective motion of the produced in the collision particles is one of such observables sensitive to the EOS of the produced matter. We present the first results for directed flow of protons with respect to the spectator symmetry plane and compare the obtained results with existing word data.

Ref. arXiv:2404.15937 [hep-ph]

Neutral triple gauge couplings (nTGCs) are absent in the Standard Model (SM) and at the dimension-6 level in the Standard Model Effective Field Theory (SMEFT), arising first from dimension-8 operators. As such, they provide a unique window for probing new physics beyond the SM. These dimension-8 operators can be mapped to nTGC form factors whose structure is consistent with the spontaneously-broken electroweak gauge symmetry of the SM. In this work, we study the probes of nTGCs in the reaction $e^{+}e^{−}$→Zγ with Z→ℓ$^{+}$ℓ$^{−}$(ℓ=e,μ) at an e$^{+}$e$^{−}$ collider. We perform a detector-level simulation and analysis of this reaction at the Circular Electron Positron Collider (CEPC) with collision energy $\sqrt{s}$ = 240 GeV and an integrated luminosity of 20 ab$^{−1}$. We present the sensitivity limits on probing the new physics scales of dimension-8 nTGC operators via measurements of the corresponding nTGC form factors.

The main goal of modern experiments in high-energy-physics area is to find deviations from the Standard Model (SM), which describe data well but is expected to be extended to a more general theory. Anomalous coupling approach provides a possibility to look for a wide range of new physics effects in different experimental signatures thanks for its model-independence. In this work the neutral triple gauge couplings (nTGCs) are considered in $ZZ(\ell\ell\nu\nu)$ and $Z(\ell\ell)\gamma$ channels, and effective field theory is used to parameterize these couplings in the Lagrangian. NTGCs are triple interactions between $Z$ bosons and photons, and some of them violate CP. Often constraints on CP-violating nTGCs are set basing on CP-conserving effects, and therefore CP violation is not probed in these studies. This work presents a study of CP-sensitive variables in the aforementioned channels using special angular variables and matrix-element-based optimal observables. Basing on these variables, one- and two-dimensional expected limits on the nTGCs are set for the conditions of Run3 at LHC experiments. This study shows the possibility to search for CP-violation using nTGC framework and special CP-sensitive variables. These variables also can be used in other channels and with different parameterizations of the Lagrangian.

The most successful theory describing elementary particles, Standard Model (SM), can not explain some already observed phenomena, so it needs an extension. Any new observed manifestation of the new physics phenomenon brings the construction of a more general theory closer, since it provides new necessary information. The study reported in this talk contains an indirect model-independent way, vertex function approach, which is used for searching more physics phenomena beyond the SM. This approach allows one to parameterize neutral triple gauge couplings (nTGC) which are prohibited in the SM. The $Z(\nu\bar{\nu})\gamma$ production in pp collisions is used to study nTGC. Expected one-dimension limits on 12 vertex parameters are set under the conditions of Run II and Run III of the ATLAS experiment (LHC). Four aforementioned parameters have not been studied at the LHC experiments before. Two-dimensional correlation contours are also studied in this work. This analysis shows that in future the most strict limits may be set by using the $Z(\nu\bar{\nu})\gamma$ production. Moreover, the problem of unitarity violation is also considered in the work. Unitarity bounds have been calculated for several coefficients, and all the limits are found to be unitarized.

Rare processes which occur via the electroweak interactions play a very important role among the vector boson production processes. Such processes are of interest both from the perspective of precision tests of the Standard Model, in particular for the investigation of the mechanism of electroweak symmetry breaking, and from the perspective of search for physics beyond the Standard Model via anomalous gauge boson couplings. One of the main difficulties in the study of EWK productions is the separation of signal events from the dominant QCD background processes of vector boson production. A series of studies have shown an additional suppression power for the vector diboson QCD production processes with respect to EWK using the third hadronic jet rapidity. In this study, we present a technique for applying the machine learning algorithms to separate the QCD and EWK processes of vector diboson production using additional information about the third jet in the case of the process of $ZZ$ pair production and subsequent decay to the $\ell\ell\nu\nu$ final state.

for the CPP/NPP collaboration

The electric and magnetic polarizabilities of a particle describe its
response to external electric and magnetic fields. The values of electric (alpha) and magnetic (beta) polarizabilities depend on the "stiffness" of the particle's constituent bonds and provide important information about its internal structure. As the lightest bound state of QCD, the pion's polarizability is measured to test Chiral Perturbation Theory
(ChPT) at low energies.

The polarizabilities of charged and neutral pions will be extracted from
experimental data obtained at Jefferson Lab. This involves measuring the cross-section of pion pair production during the interaction of a 4.5...6 GeV photon beam with a lead target via the Primakoff effect.

This talk will cover existing measurements of pion polarizability and the
current state of the experiment at Hall D in Jefferson Lab.

The muon component of the extensive atmospheric showers (EAS) is widely used in high-energy physics as a tool to study the processes of nucleus-nucleus interactions and decays of secondary particles. Information about muons with energies above 100 TeV can carry information about cosmic ray sources, as well as elements of “new physics”, so the task of measuring the energy spectrum of such muons is promising. The only instrument for measuring the energy of ultrahigh-energy muons above 100 TeV are currently the gigaton neutrino telescopes (IceCube, Baikal-GVD).
Very High Energy muons (VHE-muons), being born in the EAS, arrive at the facility accompanied by low multiplicity bundles. Such events are difficult to distinguish from events with large multiplicity bundles but without VHE-muon, since the total energy and energy release may be similar for such large bundles and single VHE-muons accompanied by small bundles. From this feature of VHE-muons, the necessity arises to develop a universal method to separate such events in gigaton neutrino telescopes.
VHE-muons tend to lose their energy stochastically, sometimes in large portions, while the energy release of low-energy muons has a less expressed stochastic character. The peak-median ratio of the longitudinal energy release profile of an event allows us to exploit this feature and identify muon bundles with ultrahigh energy muons. In this work, we analyze the spectrum of EAS muon bundles and evaluate the possibility of registering and identifying muon bundles with VHE-muons using the peak-median ratio of the longitudinal energy release profile.

A multi-component approach to the study of extensive air showers (EAS) is being implemented in the Experimental Complex (EC) NEVOD (MEPhI, Moscow). The detection of the electron-photon component of air showers is carried out by the NEVOD-EAS array, which consists of 144 scintillation counters combined into 9 clusters. The air-shower hadronic component is measured using 72 neutron detectors grouped in 12 clusters of the URAN array.

In the report, characteristics of extensive air showers detected by the EC NEVOD facilities are discussed. The accuracies of reconstructing main air-shower parameters with the NEVOD-EAS and URAN arrays have been estimated. The lateral distribution functions of EAS thermal neutrons and electron-photon component have been obtained. The spectra of air-shower size based on the data of two arrays are presented, and the reconstructed energy spectrum of primary cosmic rays is given.

New studies of extremely hot and strongly interacting matter, formed in the collision of relativistic nuclei, are proposed at the currently running Relativistic Heavy- Ion Collider (RHIC) and the Large Hadron Collider (LHC), while the colliders like FAIR (Facility for Antiproton and Ion Research) and NICA (Nuclotron-based Ion Collider fAсility) are being constructed to bring a deeper insight into the dynamics of multiparticle production in the high baryon density region of the QCD phase diagram.
These new physics programs are pushing the limits of the existing experimental research thus imposing strict requirements on the characteristics of the new detectors proposed for future applications. So-called vertex detectors are among the most demanding devices of cutting-edge research, facing extremely contradictive requirements. Among them are the closest distance to the beams collision point, minimum amount of low-Z matter along particle tracks and high thermo-mechanical stability of precisely located sensors, fine granularity and capability to work at high counting rates.
In the first part of this report, we present the major challenges existing for measurements of low-momentum charm and beauty hadrons and low-mass di-electrons formed in heavy-ion collisions at the LHC. A brief overview of the existing technology of secondary vertices identification, used in the current experiments at the LHC and RHIC, will be also provided. We will discuss in the second part of the report the existing critical items and the technological challenges to be met (the necessity of application of high-granularity sensors, the extremely minimal material budget and the high precision layout, thermo-mechanical stability and the efficient cooling). Finally, we will present the results of feasibility studies of practical solutions proposed at Saint-Petersburg State University that could be considered for the next generation of the vertex detectors including the on-going developments for the experiments at NICA collider.
The authors acknowledge Saint-Petersburg State University for a research project 95413904

The technology of two-phase emission detectors has been introduced into experimental practice at MEPhI 50 years ago. This type of detectors is extremely sensitive to ionization (down to individual electrons), can be used in very massive (on the scale of hundreds of tons) detectors in order to provide high count rate for quite rare events and organize an active shielding from natural radioactivity in the wall-les configuration of the readout systems. Emission detectors have found their unique application in the most sensitive at the moment experiments searching for cold dark matter in the form of weakly interacting massive particles (WIMPs), accelerator neutrino physics, searching for neutrino less double beta decay search and observing elastic coherent scattering of reactor neutrinos off atomic nuclei. Future prospects will be discussed.

The electromagnetic calorimeter (ECL) is one of the essential subsystems of the Belle II particle detector. The ECL consists of 8736 CsI(Tl) crystals and is designed to measure direction and momentum of detected particles in high energy range, in the conditions of high beam background. To achieve these objectives, ECL data readout system uses high sampling rate, combined with advanced waveform analysis implemented in FPGA modules. These features, in addition to slow control and reconstruction software ensure good performance of the calorimeter in current physics runs, as well as high-rate tests with 40 kHz trigger rate.

The TUS experiment became the first detector to measure the fluorescent and Cherenkov radiation of extensive atmospheric showers (EAS) in the Earth's atmosphere from space orbit. The main purpose of this experiment was to search for and study ultrahigh-energy cosmic rays with energies E > 70 Eev. The TUS detector registered dozens of anomaly events, the origin of which is unclear. During the first orbits of the satellite, the high voltage regulation system of photoelectronic multiplier tube (PMT) did not work correctly, and because of this, ~ 20% of the PMTs are dead, and the remaining ones irreversibly changed their characteristics. The anomaly events give a possibility to do a relative calibration of the photodetector matrix. The preliminary results of the calibration will be presented.

The Multi-Purpose Detector (MPD) has a main goal to investigate the hot and dense baryonic matter produced in heavy-ion collisions at the NICA collider [1]. An important subsystem of the MPD detector is the barrel electromagnetic calorimeter (ECal), which allows the high-precision measurement of the spatial coordinates and energy of photons and electrons. ECal consists of 50th half-sectors containing 768 trapezoidal “shashlyk” type towers in a projective geometry orientation [2]. Currently, the half-sectors undergo calibration on cosmic rays in two modes using inclined and longitudinal muon tracks relative to the tower axis. In simulation cosmic muons are produced on the vertical cylinder surface using a fast cosmic muon generator [3]. For inclined tracks, when at least three adjacent towers are triggered in line, the energy deposition distribution shows a clear characteristic peak and its position determines the calibartion factor. This method depends on tower position in the total ECal setup. The next one is based on the fact of signal absence in the neighboring towers in relation to the investigated one and makes it possible to identify a peak with an average energy release in the higher region. Using both methods provides a good cross-check of the calibration procedure. A self-triggering capability of the readout system gives an opportunity to calibrate the calorimeter without using external detectors. For the inclined mode, energy depositions for calibration were obtained and parametrized for all towers. The longitudinal mode is also applicable, except for towers with a nearly horizontal orientation.

Bibliography

[1] V. Abgaryan et al., Eur.Phys.J. A. 58, 140 (2022).

[2] M. Bhattacharjee et al., Phys.Part.Nucl. 55, 803 (2024).

[3] V.A. Baskov et al., Phys.Part.Nucl. 52, 663 (2021).

The Multi-Purpose Detector (MPD) is a heavy-ion experiment of the NICA complex under construction at JINR, Russia. With heavy-ion collisions in collider and fixed-target modes, MPD will be able to cover the energy range $\sqrt{s_{NN}}=2.4-11$ GeV and thus study the baryon-rich region of the QCD phase diagram. Commissioning of the MPD detector with Xe/Bi beams is expected in late 2025. The trigger system of the MPD detector includes several subsystems covering the forward and central rapidity regions. In this contribution, we review the performance of the system for the collider and fixed-target modes of operation, and discuss the implications for the system size and the collision energy scans needed for successful implementation of the NICA physics program.

A highly-granular neutron detector is currently being developed for the BM@N experiment at JINR, Dubna, Russia, aimed at measuring neutrons produced in nuclear collisions within the energy range of 1-4 AGeV. The detector consists of alternating layers of scintillators and absorbers, with silicon photomultipliers used to capture light signals. Data readout is handled by a single-threshold multichannel TDC. This work presents an analytical approach to characterizing the signals from plastic scintillator detectors read out by SiPMs, which is fundamental to understanding the relationship between Time-over-Threshold (ToT) and signal amplitude. The analysis addresses slewing corrections essential for improving the detector's time resolution and the time calibration procedure.

Optical modules which consist of photomultipliers and wavelength shifting (WLS) plates are considered as photosensors for water Cherenkov detectors. A WLS plate absorbs Cherenkov light and reemits it at longer wavelengths. The reemitted light is then detected by a PMT. Such an optical module allows to increase the efficiency of the Cherenkov light detection by a factor of 2 . This report will describe the design of modules, optimization of the concentration of WLS dopants, and present the results of measurements of parameters of WLS plates and PMTs, including the light yield, efficiency, and dark rate. Selection of a reflector will be also discussed, as as well the study of plates aging using high temperature tests.

The Highly Granular Neutron Detector (HGND) is designed for the BM@N experiment to study neutron emission in heavy ion collisions at beam energies up to 4A GeV. This detector allows the identification of neutrons and the reconstruction of their energies using time-of-flight method, facilitating the assessment of neutron yields and azimuthal flow. The challenging neutron energy range of $0.5-4$ GeV and large background contributions require sophisticated reconstruction algorithms. In this contribution, we present a machine learning-based approach to the neutron reconstruction problem and discuss preliminary results of the proposed algorithm.

BM@N (Baryonic Matter at Nuclotron) is the first fixed target experiment collecting data at the NICA accelerator. The goal of BM@N physics program is a study of highly compressed nuclear matter in heavy ion beams. The Nuclotron provides heavy ion beams with energies from 2.3 to 4.5 AGeV, which is suitable for studies of strange mesons and multi–strange hyperons produced in nucleus-nucleus collisions close to the kinematic threshold.
The BM@N experiment collected its initial data using a carbon beam with kinetic energies of 4.0 and 4.5 AGeV and a set of solid targets, including Al, C, Cu, and Pb. This paper outlines the methodology for calculating cross sections and measuring yields in the Λ→p+π- decay channel. Additionally, the results include estimates of the temperature inside the fireball, obtained from the inverse distributions of transverse momenta.

Neutron energy spectra were measured in the energy range 2 – 200 MeV for emission angles of 95°, 110° and 121° in collisions of 124Xe nuclei with a CsI target at a beam energy of 3.8 GeV/nucleon. The measurement was carried out with a compact TOF spectrometer in the last run of the BM@N experiment. The spectrometer characteristics and data analysis are discussed. The studied region of angles corresponds to neutrons emitted during the decay of spectators of the target nuclei. The resulting neutron energy spectra are well described by phenomenological model of three moving sources. In the energy region below 15 MeV, the angular distribution is isotropic. It indicates that the velocity of this neutron source is close to zero. The obtained neutron spectra are compared with results of theoretical models.

This work is devoted to the search for phi mesons after collision of Xe beams with a CsI target at E = 3.8 AGeV at the BM@N experiment (JINR, Dubna). Both MC and experimental data were considered and peaks in the invariant mass distribution corresponding to phi mesons were obtained. Analysis of reconstruction efficiency was performed. The future aim is to increase our understanding of the transition from baryonic matter to (quark-gluon plasma) QGP.

The Multi-Purpose Detector (MPD), currently under construction at the NICA complex at JINR, is designed to be the primary experiment for studying heavy-ion collisions in the energy range of $\sqrt{s_{NN}}$ =4−11 GeV. The MPD aims to explore the baryon-rich region of the QCD phase diagram to investigate the possible existence of a first-order phase transition and a critical end-point. The measurement of direct photon and neutral meson production is a key part of the MPD physics program.

We will present results of physics feasibility studies for photon and neutral mesons ($\pi^{0}$ and η) reconstruction with the MPD detector in Bi+Bi collisions at $\sqrt{s_{NN}}$ = 9.2 GeV simulated using realistic event generators. Photon measurements are performed using two methods, including the identification of photon clusters in the electromagnetic calorimeter (ECAL) and the reconstruction of photons in the tracking system as dielectron pairs produced through conversions in detector materials (PCM). Neutral meson signals are analyzed using the invariant mass method by combining photon pairs from ECAL-ECAL, PCM-PCM, and ECAL-PCM sources, with the uncorrelated combinatorial background estimated through the event-mixing technique. The measured $\pi^{0}$ and η transverse momentum spectra are compared to truly generated ones to estimate robustness of the developed reconstruction procedures.

Study of the strangeness production in heavy-ion collisions is one
the primary goals of the MPD experiment at the NICA collider. To
collect sufficient statistics of (multi)strange particle decays,
their efficient selection from the high combinatorial background
is required. Presumably, solution of such a task can greatly benefit
from multivariate analyses based on machine learning techniques.
In this work, results of application of the machine learning approaches,
implemented in the TMVA package of the ROOT framework, are presented
for Monte Carlo data event samples of heavy-ion collisions and compared with the results of the topological cuts selection method.

In high-energy hadronic collisions neutral meson spectra can be measured with high precision in a wide range of transverse momenta, providing valuable input for the nucleon structure functions parametrization and for studying in great detail the cold and hot matter effects.

The ALICE experiment at the LHC provides the possibility to measure photons in large acceptance EMCAL or precise PHOS calorimeters and to reconstruct photons converted in e+e- pairs and reconstructed in the central tracking system. Simultaneous measurement of neutral meson spectra with different methods provides good cross-check of the measurements and allows one to dramatically reduce uncertainties.

In this talk we present recent results from ALICE on the neutral meson measurements in pp, p--Pb, and Pb--Pb collisions at LHC energies based on the data collected in LHC Run 2 and the performance of ALICE in LHC Run 3.

The primary purpose of the ALICE experiment at the Large Hadron Collider (LHC) is to study the properties of nuclear matter at extremely high temperatures and energy density produced by relativistic nucleus-nucleus collisions. During the Long Shutdown 2 (2019-2022), new detectors were incorporated into the ALICE setup, including a Fast Interaction Trigger (FIT). The FIT detector system consists of three sub-detectors based on different technologies: FDD, FT0 and FV0. In addition to online functionality, the FIT data are used offline for multiplicity, centrality, collision time, event-plane determination, vertex position, and veto for diffractive and ultra-peripheral heavy-ion collisions. These global observables are essential for event characterization and the study of nuclear matter properties. This presentation will give a preliminary overview of FIT's performance in the extraction of global observables from pp and A-A collisions during the LHC Run 3.

In non-central A+A collisions, the measured azimuthal flow of particles is well understood in the paradigm of quark-gluon plasma formation. Namely, the initial spatial anisotropies in the intersection region of the overlap of two nuclei are transferred under large pressure gradients by the almost perfect liquid consisting of strongly coupled quarks and gluons to the momentum asymmetries of final hadrons. In turn, the same explanation is not straightforwardly applicable to the surprising evidence of azimuthal anisotropies recently observed in high-multiplicity p+p collisions at LHC as the produced matter may not be thermalized in such a small droplet. In this report, the new model that does not involve the hydrodynamic phase of the system evolution but can describe the long-range azimuthal correlations will be presented. It is based on the formation in a p+p inelastic interaction a number of colour (quark-gluon) strings that are finite in rapidity. We consider string attraction and fusion as well as interactions of produced particles with string medium. Results on two-particle angular correlations and flow harmonics will be presented.

The authors acknowledge Saint-Petersburg State University for a research project 95413904.

Elastic pp scattering at the invariant mass of the pp-system $\sqrt{s_{pp}}= 3 - 5$
GeV and large c.m.s. angles ($\theta_{cm}=90^\circ$) demonstrates a
very large double-spin correlation [1]. These kinematical region corresponds to very high momentum trasfer |t|
where quark counting rules are valid and color transparency is expected to be observed. On the other hand,
these energies correspond to the thresholds for strangeness (~ 3 GeV) and charm (~5 GeV) production in pp collisions, respectively. As was shown in [2], the observed strong correlations (cross-section ratio of 4 : 1 for parallel and antiparallel spins of colliding protons) are compatible with the assumption of the formation of uudss̄uud and uudcc̄uud octoquark resonances in the s channel. Moreover, on the basis of this assumption, the authors of Ref. [2] also explained qualitatively an unusual behavior of the color transparency in reactions of the A(p, 2p)B type and oscillations in the differential cross section
dσ/dt for elastic pp scattering in the region of manifestation of quark counting rules. However, the last two effects have a different explanation within the nuclear-filtering model [3]. In this connection one should note that hard dynamics in elastic pp and pn-scattering may be markedly different, because the pn-scattering includes the isoscalar channel in addition to the isovector one. In view of this, it is of importance to study the doubly polarized channel of elastic pn scattering in the same energy range of 3-5 GeV. In principle, this may be done at the SPD in the dd collisions [4]. We studied [5] double spin correlation of the reaction dd-> pnpn within the impulse (double pole) approximation and found that at zero relative momenta of nucleons in both deuterons, when the deuteron S-wave dominates, the transversal and longitudinal- correlation coincides with the similar double-spin correlation in pp or pn- elastic large angle scattering. Effects of rescatterings and the D-wave contribution are under consideration.

The research is supported under the Scientific Program JINR – Republic of Kazakstan.

[1] D. G. Crabb, R. C. Fernow, P. H. Hansen, et al. Phys. Rev. Lett. 41, 1257 (1978).

[2] S. J. Brodsky and G. de Teramond, Phys. Rev. Lett. 60, 1924 (1988).

[3] J. P. Ralston and B. Pire, Phys. Rev. Lett. 49, 1605 (1982).

[4] V. Abramov et al. Phys. Part. Nucl. 52, 1044 (2021).

[5] Yu. Uzikov, A. Temerbayev, Phys. Part. Nucl. 55, N4, 895 (2024).

Extensive air showers (EAS), produced by cosmic rays in the atmosphere, serve as probes of particle interactions, providing access to energies and kinematical regimes beyond the reach of laboratory experiments. Measurements from multiple cosmic-ray detectors indicate a significant, yet unexplained, discrepancy between the observed muon content in EAS and that predicted by state-of-the-art interaction models, suggesting a need for refinements in our understanding of fundamental physics. Here we show that a tiny, experimentally allowed, violation of the Lorentz invariance may result in the suppression of the number of electrons in EAS, leaving the muon number intact and explaining both the ''muon excess'' and its energy dependence. Future experimental tests of this scenario are outlined.