BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Dark Energy models DTSTART;VALUE=DATE-TIME:20261030T100500Z DTEND;VALUE=DATE-TIME:20261030T102000Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6532@cern.ch DESCRIPTION:Speakers: Vyacheslav Dokuchaev (Institute for Nuclear Research of the Russian Academy of Sciences)\nMatter consists of particles and fie lds\, and more consistently only of quantum fields. Particles are the loca lized excitations of quantum fields. Sometimes fermions are called ``matte r’’ and bosons are called ``fields’’. Definition: the component o f the Universe is called ``dark’’ if it does not emit the light. \n\n{ \\bf Basic components of observable Universe}: \n\n70\\% is the `dark fiel d’ or `Dark Energy’ (DE)\, which is the dominating component of the Un iverse in the modern Standard Astrophysical Model (named also the Cosmolog y of High Accuracy). Dark Energy is either filling up all Universe with ne gative pressure\, p95$\\%) is unknown!\n\nThe incomplete and replenished l ist of Dark Energy models:\n\nGeneral Relativity framework:\nquintessence DE\, $k$-essence DE\, Born-Infeld DE\; BKS condensate DE\, ghost- condensa te DE\, et al.\n\nGeneral Relativity modifications:\n$f(R)$ gravity DE\, G auss-Bonnet DE\, holographic gravity\, super-string gravity\, quantum-enta ngled gravity et al.\n\n%The term ``Dark Energy'’ is ungrammatical. Ther e must be some carrier for energy. The energy itself can not be ``dark’' or ``bright’'. \nIt is more reasonable to say on the ``dark field’' o r ``invisible field'’.\nMeanwhile\, the term ``Dark Energy'’ becomes c onventional and accepted by scientific community.\n\nInterpretation of the experiment is impossible without theoretical models\, ideas and concepts. The problem of ``Dark Energy’' is the interrelation between the experim ent and the theory!\n\nTheoretical modeling is based on:\n(1) Scientific m ethod: experiment as criterion of truthfulness (Francis Bacon and Karl Pop per)\; (2) criterion of beauty: the theory must be beautiful (Occam’s ra zor)\; (3) Criterion of novelty: the theory must be novel and must provide s new effects and phenomena\; (4) criterium of liberty: all is allowed\, i f not forbidden.\n\n{\\bf After all\, what is Dark Energy? We don’t know !}\n\nhttps://indico.particle.mephi.ru/event/626/contributions/6532/ LOCATION: Conference Hall 1 URL:https://indico.particle.mephi.ru/event/626/contributions/6532/ END:VEVENT BEGIN:VEVENT SUMMARY:Impact of primordial plasma on the collapse of bubble walls and pr imordial black hole formation DTSTART;VALUE=DATE-TIME:20261029T073000Z DTEND;VALUE=DATE-TIME:20261029T074500Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6527@cern.ch DESCRIPTION:Speakers: Danila Filippov (NRNU MEPhI)\nThe interaction of a c losed domain wall with the primordial plasma during the radiation-dominate d stage of the Universe is studied. When the plasma temperature drops belo w a threshold value determined by the wall potential parameters\, the wall becomes opaque\, trapping plasma inside. Relativistic hydrodynamic simula tions of the trapped plasma and the wall dynamics are performed. The crite rion for the wall to remain spherical during collapse is established\, jus tifying the use of the thin-wall equation of motion. The pressure of the t rapped plasma is shown to counteract the surface tension and\, for a certa in range of parameters\, to prevent the collapse into a primordial black h ole\, causing the wall to bounce and launch a shock wave into the surround ing plasma. The propagation distance of this shock wave and the associated heating of the external medium are estimated.\n\nhttps://indico.particle. mephi.ru/event/626/contributions/6527/ LOCATION: Conference Hall 5 URL:https://indico.particle.mephi.ru/event/626/contributions/6527/ END:VEVENT BEGIN:VEVENT SUMMARY:Photon sphere for a dyonic black hole corresponding to A_2 Toda chain DTSTART;VALUE=DATE-TIME:20261030T064500Z DTEND;VALUE=DATE-TIME:20261030T070000Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6271@cern.ch DESCRIPTION:Speakers: Vladimir Ivashchuk (SRCAM Rostest/RUDN University)\n We consider a dilatonic dyon black hole solution\n with a gravitational ra dius of $2 \\mu$ and two charges\, \n $Q_1$ (electric) and $Q_2$ (magnet ic)\, within the framework \n of a four-dimensional gravitational model co mprising one scalar field and one 2-form. The dilaton coupling constant $ \\lambda$ is fixed by $\\lambda^2 = \\frac{3}{2}$. This solution is relat ed to the $A_2$ Toda chain. \n The circular orbits of null geodesics are e xplored\, and the fifth-order polynomial master equation governing the ph oton sphere radius $R_0$\n is analyzed. It is shown to admit a unique solu tion satisfying $R_0 > 2 \\mu$. \n The circular null geodesics are proven to be unstable. \n Finally\, the black hole shadow is examined\, yielding relations \n for the shadow angle and the critical impact parameter.\n\nh ttps://indico.particle.mephi.ru/event/626/contributions/6271/ LOCATION: Conference Hall 4 URL:https://indico.particle.mephi.ru/event/626/contributions/6271/ END:VEVENT BEGIN:VEVENT SUMMARY:• Tunneling into the Past: Quantum Creation of Time Machines DTSTART;VALUE=DATE-TIME:20261030T073000Z DTEND;VALUE=DATE-TIME:20261030T074500Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6272@cern.ch DESCRIPTION:Speakers: Victor Kuryan ()\nOne of the predictions of general relativity is the existence of spacetimes with nontrivial topology and cau sal structure. In principle\, the real three-dimensional space could be mu ltiply connected and could contain wormholes. As shown in the work of Novi kov\, a stable wormhole—if such an object exists—could\, in principle\ , be turned into a time machine. When quantum field fluctuations are taken into account in a spacetime containing such a wormhole\, these fluctuatio ns grow significantly as the Cauchy horizon is approached. In particular\, the renormalized stress energy tensor of the quantum field diverges at th e Cauchy horizon\, leading to an infinite energy density. This divergence is commonly interpreted as a sign that building a time machine is impossib le—this is the essence of the chronology protection conjecture. However\ , that conclusion was reached by treating the wormhole throats' motion cla ssically and by evaluating quantum effects in a fixed background geometry. \nIn contrast\, in the present paper we apply quantum mechanics to describ e the motion of the wormhole throats. Within this approach\, we obtain an estimate for the probability of creating a time machine\, and this probabi lity is found to be of order unity. The process closely resembles quantum tunnelling as known from ordinary quantum mechanics.\n\nhttps://indico.par ticle.mephi.ru/event/626/contributions/6272/ LOCATION: Conference Hall 4 URL:https://indico.particle.mephi.ru/event/626/contributions/6272/ END:VEVENT BEGIN:VEVENT SUMMARY:Quasinormal modes in the field of a dyon-like dilatonic black hole corresponding to $A_1 + A_1$ Toda chain DTSTART;VALUE=DATE-TIME:20261030T070000Z DTEND;VALUE=DATE-TIME:20261030T071500Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6273@cern.ch DESCRIPTION:Speakers: Vladimir Ivashchuk (Rostest/RUDN)\nWe explore the qu asinormal modes of a massless test scalar field in the gravitational backg round of a non-extremal dilatonic dyonic black hole. The dyon-like black hole solution is considered within a four-dimensional gravitational model that includes two scalar fields and two 2-forms. \n It is governed by two dilatonic coupling vectors \\(\\vec{\\lambda}_s\\) (with \\(s=1\,2\\)) t hat satisfy \\(\\vec{\\lambda}_1 = \\vec{\\lambda}_2 = \\vec{\\lambda}\\) and \\(\\vec{\\lambda}^2 = 1/2\\). We derive and examine the quasinormal modes of a massless scalar test field in the eikonal limit. \nThese modes are governed by the solution parameters $\\mu > 0$\, $P_1 > 0$\, and $P_2 > 0$. In the two limiting scenarios -- namely $P_1 = P_2 = 0$ and $P_1 = P _2 = P > 0$ -- our results reduce exactly to the known (eikonal) quasinorm al spectra for the Schwarzschild and Reissner-Nordström black holes\, re spectively.\nNumerical higher-order WKB analysis of quasinormal frequencie s for two lower levels (for various values of parameters) is also presente d.\n\nhttps://indico.particle.mephi.ru/event/626/contributions/6273/ LOCATION: Conference Hall 4 URL:https://indico.particle.mephi.ru/event/626/contributions/6273/ END:VEVENT BEGIN:VEVENT SUMMARY:Astronomical Tests of Spatial Anisotropy of Gravity: Lunar Laser R anging and Trans-Neptunian Object Anomalies in the Context of the Spin-Den sity Model DTSTART;VALUE=DATE-TIME:20261030T074500Z DTEND;VALUE=DATE-TIME:20261030T080000Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6274@cern.ch DESCRIPTION:Speakers: Sergei Kupreev (RUDN University)\nSpatial anisotropy of the gravitational constant $G$ is a key prediction of the Spin-Density Model (SDM)\, in which space-time is considered as a dynamic carrier medi um. According to the SDM\, large-scale polarization of this medium by acti ve galactic nuclei leads to a dependence of the effective gravitational co nstant on direction\, manifesting as a difference in gravitational attract ion in the Galactic plane and perpendicular to it. The astrophysical estim ate of this effect gives $\\Delta G/G \\sim 10^{-8}$\, whereas in laborato ry conditions on Earth the effect should be suppressed by the local gravit ational field to $\\Delta G/G \\sim 10^{-10}$. Existing gravimetric constr aints ($\\Delta G/G \n\nhttps://indico.particle.mephi.ru/event/626/contrib utions/6274/ LOCATION: Conference Hall 4 URL:https://indico.particle.mephi.ru/event/626/contributions/6274/ END:VEVENT BEGIN:VEVENT SUMMARY:Particle creation in the Early Universe: comparing canonical and p ath integral approaches DTSTART;VALUE=DATE-TIME:20261030T061500Z DTEND;VALUE=DATE-TIME:20261030T063000Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6275@cern.ch DESCRIPTION:Speakers: Tatyana Shestakova (Department of Theoretical and Co mputational Physics\, Southern Federal University)\nWe consider particle c reation of a non‑conformal scalar field in the Early Universe. The devia tion from conformality is assumed to be small\, which allows us to treat t he terms describing the non-conformal scalar field as a perturbation. We d erive the Schrödinger equation for the system of gravitational and scalar fields from the path integral making use of a holomorphic representation for the scalar field. In the conformal case\, the equation is solved exact ly. In the case of a non-conformal field\, we use the perturbation theory\ , and some new features are revealed. When deriving the Schrödinger equat ion\, we obtain an operator that maps the states of the Fock space with a certain number of particles and antiparticles at time *t* to states corres ponding to a subsequent moment of time. The operator appears entirely due to changing of a basis in the Fock space with time. We compare our results with those obtained using the method of diagonalizing the Hamiltonian in the canonical formalism and find that the results are fully consistent. In perspective\, we consider the path integral approach as an additional too l for studying particle creation in a gravitational field and cosmological perturbations.\n\nhttps://indico.particle.mephi.ru/event/626/contribution s/6275/ LOCATION: Conference Hall 4 URL:https://indico.particle.mephi.ru/event/626/contributions/6275/ END:VEVENT BEGIN:VEVENT SUMMARY:Vacuum restructuring and scalar particle production in a closed is otropic universe DTSTART;VALUE=DATE-TIME:20261030T063000Z DTEND;VALUE=DATE-TIME:20261030T064500Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6276@cern.ch DESCRIPTION:Speakers: Roger Ivan Ayala Oña (Southern Federal University)\ , Tatyana Shestakova (Department of Theoretical and Computational Physics\ , Southern Federal University)\nWe study scalar particle production in a c losed isotropic universe within the extended phase space approach. Unlike the treatments in which the gravitational field is treated classically\, w e quantize the coupled gravitational and matter degrees of freedom and der ive the Schrodinger equation for the wave function of the Universe\, inclu ding perturbative contributions associated with a slight deviation from co nformal coupling. We start from the effective action for scalar and spinor fields interacting with gravity\, with the spinor field introduced to can cel vacuum divergences arising in the theory. The gravitational degree of freedom is described in the coordinate representation\, while the matter m odes are treated in the holomorphic representation. We then analyze partic le-production processes as perturbative transitions between quantum states . Unlike the usual path-integral treatment\, where perturbations are assum ed to be independent of velocities\, the perturbative interaction in our m odel depends on the time derivative of the scale factor. We compare this d escription with the conventional canonical approach based on Bogoliubov tr ansformations and discuss the relation between the two formulations.\n\nht tps://indico.particle.mephi.ru/event/626/contributions/6276/ LOCATION: Conference Hall 4 URL:https://indico.particle.mephi.ru/event/626/contributions/6276/ END:VEVENT BEGIN:VEVENT SUMMARY:Non-Conserved Gravity: A Thermodynamic Origin of Cosmic Accelerati on DTSTART;VALUE=DATE-TIME:20261030T071500Z DTEND;VALUE=DATE-TIME:20261030T073000Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6277@cern.ch DESCRIPTION:Speakers: Seyed Hamidreza Fazlollahi (RUDN)\nWe present a new gravitational framework in which the conventional conservation of the ener gy-momentum tensor is relaxed and replaced by a non-conservation law motiv ated by relativistic thermodynamics. In this approach\, the exchange of en ergy and momentum between matter and the gravitational sector is treated a s a fundamental physical effect rather than as an effective description of an unknown dark-energy component. The resulting field equations extend Ei nstein gravity while retaining the standard geometric description of space time and the usual conservation law as a limiting case.\n\nWe investigate the cosmological consequences of this non-conserved gravitational dynamics in a homogeneous and isotropic universe. The modified continuity equation introduces an additional matter–spacetime exchange term\, which changes the evolution of the cosmic energy density and generates an effective con tribution to the expansion dynamics. Remarkably\, the resulting cosmologic al evolution can produce a transition from decelerated to accelerated expa nsion without introducing a fundamental cosmological constant or an exotic dark-energy fluid. For suitable parameters\, the background evolution app roaches the behavior of the standard $\\Lambda$CDM model while providing a different physical interpretation of the source of late-time acceleration .\n\nThe framework therefore offers a thermodynamically motivated alternat ive to the conventional dark-energy picture and provides a direct connecti on between gravitational dynamics\, energy exchange\, and cosmological evo lution. We discuss the corresponding expansion history and the prospects f or confronting the model with observational cosmology\, including distance -redshift measurements and the evolution of the Hubble parameter. The resu lts suggest that violations of energy-momentum conservation\, when consist ently incorporated into gravitational thermodynamics\, may provide a viabl e route toward understanding cosmic acceleration without requiring an inde pendent dark-energy sector.\n\nhttps://indico.particle.mephi.ru/event/626/ contributions/6277/ LOCATION: Conference Hall 4 URL:https://indico.particle.mephi.ru/event/626/contributions/6277/ END:VEVENT BEGIN:VEVENT SUMMARY:Latest results from DES Y6 DTSTART;VALUE=DATE-TIME:20261030T083000Z DTEND;VALUE=DATE-TIME:20261030T085000Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6265@cern.ch DESCRIPTION:Speakers: Martín Rodríguez Monroy (CSFK Konkoly Observatory) \nWe present the Dark Energy Survey Year 6 3x2pt analysis\, which combines cosmic shear\, galaxy clustering\, and galaxy-galaxy lensing measurements across ~4000 deg². Using an unprecedented sample of lens and source gala xies\, this study delivers some of the most precise constraints to date on key cosmological parameters\, including the matter density Ωₘ and the amplitude of cosmic structure σ₈. Our findings reveal a mild but intrig uing tension with Planck CMB predictions under the standard ΛCDM mode. Th is analysis demonstrates the power of joint probes in testing dark energy and sets a benchmark for upcoming surveys like LSST and Euclid.\n\nhttps:/ /indico.particle.mephi.ru/event/626/contributions/6265/ LOCATION: Conference Hall 1 URL:https://indico.particle.mephi.ru/event/626/contributions/6265/ END:VEVENT BEGIN:VEVENT SUMMARY:Search for traversable wormholes using astrophysical methods DTSTART;VALUE=DATE-TIME:20261030T090500Z DTEND;VALUE=DATE-TIME:20261030T092000Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6266@cern.ch DESCRIPTION:Speakers: Olga Sazhina (SAI MSU)\, Iurii Moiseev (SAI Lomonos ov MSU)\nWe present simulated detectability of traversable wormholes (WHs) in wide binary astrophysical systems without accretion (dormant binary sy stems) and in the Galactic center. The wormhole spacetime is represented a s a gluing of two asymptotically flat Schwarzschild spacetimes\, without s pecifying the detailed geometry of the throat. We consider a traversable W H candidate as a compact object in a binary system\, whose companion star is perturbed by a massive object on an elliptical orbit on the other side of the WHthroat. In the case of a supermassive BH as WH candidate the pert urbing acceleration is analyzed and compared with the stochastic gravitati onal influence of surrounding stars. For dormant wide binary systems\, we analyze the radial velocity perturbations and their distinguishability fro m triple-system scenario. Under the model assumptions and the considered o bservational sampling\, radial velocity perturbations are detectable in si mulations with an observational accuracy of 1.5 km/s for all considered ob servation time spans. For a more conservative accuracy of 10 km/s\, the sp ectral analysis methods become statistically significant after ≈ 17 year s of simulated data accumulation. The spectral and non-parametric methods significantly reduce the required accumulation time compared to matched-fi ltering applied in isolation.\n\nhttps://indico.particle.mephi.ru/event/62 6/contributions/6266/ LOCATION: Conference Hall 1 URL:https://indico.particle.mephi.ru/event/626/contributions/6266/ END:VEVENT BEGIN:VEVENT SUMMARY:Two-brane structure and its manifestation DTSTART;VALUE=DATE-TIME:20261030T092000Z DTEND;VALUE=DATE-TIME:20261030T093500Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6267@cern.ch DESCRIPTION:Speakers: Konstantin Prokopev (MEPhI)\nWe study the neutrino s ector of an eight-dimensional two-brane model based on $f(R)$ gravity. The metric is warped:\n\n$ds^{2} = e^{2\\gamma(u)}\\eta_{\\mu\\nu}dx^{\\mu}dx ^{\\nu} - du^{2} - r^{2}(u)\\\,d\\Omega^{2}_{n-1}.$\n\nHere $u$ is the rad ial extra coordinate\, and the remaining three coordinates parametrise a c ompact internal manifold. The classical field equations admit a countable family of solutions in which $\\gamma(u)$ and $r(u)$ vanish at two endpoin ts $u_{1}$ and $u_{2}$. Matter fields accumulate near these endpoints. A p air of four-dimensional branes therefore forms spontaneously\, as a soluti on of the gravitational dynamics. Nothing is assumed about their existence \, position or tension.\n\nWe then derive the consequences of this geometr y for the matter sector. Massless bulk fermions obey\n\n$\\left(\\partial_ {u} + \\frac{\\partial_ur^{}(u)}{2r(u)} + 2\\partial_u\\gamma(u)\\right) Y (u) = 0$\n\nalong $u$. The solution is sharply peaked at $u_{1}$ and $u_{2 }$. On the compact factor\, a normalisable chiral zero mode requires a sui table background gauge field. Each bulk fermion then has one chiral zero m ode per brane\, and the two sets of modes are effectively decoupled\, beca use $|Y(u)|^{2}$ is exponentially small between the branes. The Higgs vacu um expectation value differs on the two branes\, so masses and couplings o n brane-2 are free up to $m_{D}$. The gauge zero mode behaves differently: it is constant along $u$\, so the $Z$ boson is common to both branes.\n\n Dimensional reduction of the neutral-current action reflects this structur e. Besides the canonical on-brane vertices\, it produces off-diagonal neut rino–$Z$ couplings weighted by the overlap of the two profile functions. Exponential localisation makes this overlap of order $\\exp\\left[-m(u_{2 }-u_{1})\\right]$\, that is about $10^{-35}$ for an interbrane distance $u _{2}-u_{1} \\approx 80\\\,m_{D}^{-1}$ and $m \\sim 1$. The geometry thus s upplies an exponentially small parameter without fine-tuning. A seesaw wit h the brane-2 vacuum expectation value places a superheavy sterile neutrin o on the hidden brane\, and the off-diagonal vertex lets it decay at a rat e suppressed by the squared overlap. The resulting lifetime is cosmologica l\, so the particle is a dark-matter candidate.\n\nThe decay $\\nu^{(2)} \ \to \\nu^{(1)} Z^{\\ast} \\to \\nu^{(1)}\\nu^{(1)}\\bar{\\nu}^{(1)}$ gives a quasi-monochromatic flux peaked at $E_{\\nu} \\sim m_{2}$. We estimate the diffuse rate and compare it with IceCube and KM3NeT data\, including K M3-230213A at $2.2 \\times 10^{8}\\\,\\mathrm{GeV}$. The competing annihil ation channel $\\bar{\\nu}^{(2)}\\nu^{(2)} \\to Z^{\\ast} \\to \\bar{\\nu} ^{(1)}\\nu^{(1)}$ falls about 18 orders of magnitude short\, because its p roduction rate scales as $m_{2}^{-4}$.\n\nhttps://indico.particle.mephi.ru /event/626/contributions/6267/ LOCATION: Conference Hall 1 URL:https://indico.particle.mephi.ru/event/626/contributions/6267/ END:VEVENT BEGIN:VEVENT SUMMARY:Causal Space-Time Structure and non-Hausdorff Extension of Schwarz schild Black Hole Interior DTSTART;VALUE=DATE-TIME:20261030T095000Z DTEND;VALUE=DATE-TIME:20261030T100500Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6268@cern.ch DESCRIPTION:Speakers: Asya Aynbund (MIPT)\nCones of future and past are ri gorously constructed under the horizon of black hole by completions of geo desics continued from causally connected space-time regions outside the bl ack hole interior. Treating the Schwarzschild black hole as a zero charge limit of Reissner—Nordsrom black hole reforms the Penrose—Carter diagr am into the infinite band that excludes the closed proper-time cycles unde r the geodesic motion. The marginal trajectories between the cones of fut ure and past compose paths common with a compact non-Hausdorff spherical e xtension of black hole interior forming the thermal bath for particles fal len to the black hole.\n\nhttps://indico.particle.mephi.ru/event/626/contr ibutions/6268/ LOCATION: Conference Hall 1 URL:https://indico.particle.mephi.ru/event/626/contributions/6268/ END:VEVENT BEGIN:VEVENT SUMMARY:Towards N-body Modelling of Self-Interacting Dark Matter Structure s with GIZMO DTSTART;VALUE=DATE-TIME:20261030T093500Z DTEND;VALUE=DATE-TIME:20261030T095000Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6269@cern.ch DESCRIPTION:Speakers: Dmitry Kalashnikov (NRNU MEPhI)\nThe standard cosmol ogical model $\\Lambda\\mathrm{CDM}$\, successfully describes large-scale structure of the Universe. However\, several problems on galactic scales m otivate studies of alternative dark matter (DM) models. One of such models is self-interacting dark matter (SIDM)\, where interactions between DM pa rticles can change the internal structure of DM halos.\n \nIn previous stu dies\, our group considered SIDM models with a dark interaction as a possi ble explanation of the cosmic-ray positron excess. An important question f or such models is whether a two-component DM distribution can be formed dy namically\, where one component creates a separate spatial structure and c ontributes to the positron signal.\nIn this work\, we develop $N$-body sim ulation framework based on GIZMO to study this problem. At the current sta ge\, we compare collisionless CDM and SIDM halos and study the evolution o f their density profiles\, the formation of SIDM cores\, and the dependenc e of these effects on the interaction parameters. These simulations are al so used to test and validate the numerical setup.\nThe next step is to ext end the simulations to two-component DM models and study the conditions un der which the required spatial distributions can form and remain dynamical ly stable. This approach allows us to connect the microscopic properties o f SIDM models with the formation and evolution of DM structures relevant f or indirect DM searches.\n\nhttps://indico.particle.mephi.ru/event/626/con tributions/6269/ LOCATION: Conference Hall 1 URL:https://indico.particle.mephi.ru/event/626/contributions/6269/ END:VEVENT BEGIN:VEVENT SUMMARY:Exceptional wormholes in scalar-tensor gravity DTSTART;VALUE=DATE-TIME:20261030T085000Z DTEND;VALUE=DATE-TIME:20261030T090500Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6270@cern.ch DESCRIPTION:Speakers: Kirill Bronnikov (VNIIMS)\nIn the Bergmann-Wagoner-N ordtvedt class of scalar-tensor theories\, well known are wormhole solutio ns existing in the phantom sector of the theory. Exceptional wormholes exi st in the canonical sector owing to the phenomenon of conformal continuati on\, the situation where the Einstein frame manifold maps to only a region of the Jordan frame manifold\, and the latter is smoothly continued to a region with negative effective gravitational coupling. We discuss the exis tence conditions and the stability properties of exceptional wormholes\, i n particular\, those with and without an electromagnetic field in the Bran s-Dicke theory: it is shown how the electromagnetic field plays a stabiliz ing role.\n\nhttps://indico.particle.mephi.ru/event/626/contributions/6270 / LOCATION: Conference Hall 1 URL:https://indico.particle.mephi.ru/event/626/contributions/6270/ END:VEVENT BEGIN:VEVENT SUMMARY:Dynamical attractors in early Universe models: Bounce and Genesis scenarios DTSTART;VALUE=DATE-TIME:20261029T151000Z DTEND;VALUE=DATE-TIME:20261029T152500Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6255@cern.ch DESCRIPTION:Speakers: Andrey Sharofeev (MSU & INR RAS)\nBouncing cosmologi es and Galilean Genesis provide alternative scenarios to the standard infl ationary paradigm. An important question for such models is whether their characteristic cosmological backgrounds exhibit dynamical attractor behavi our\, making their evolution insensitive to a broad class of initial condi tions. In this talk\, I will discuss the attractor properties of bouncing and Galilean Genesis scenarios and examine the conditions under which the corresponding cosmological solutions can be regarded as dynamically robust .\n\nhttps://indico.particle.mephi.ru/event/626/contributions/6255/ LOCATION: Conference Hall 5 URL:https://indico.particle.mephi.ru/event/626/contributions/6255/ END:VEVENT BEGIN:VEVENT SUMMARY:Stability of monopole perturbations in Horndeski theory on a dynam ical spherically symmetric background DTSTART;VALUE=DATE-TIME:20261029T144000Z DTEND;VALUE=DATE-TIME:20261029T145500Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6256@cern.ch DESCRIPTION:Speakers: Kirill Kiselev (M.V. Lomonosov Moscow State Universi ty)\nConstructing physically viable models within Horndeski and Beyond Hor ndeski theories requires strict checks to avoid ghost and gradient instabi lities\, yet the corresponding stability constraints for dynamical spheric ally symmetric backgrounds remain incomplete. Previous studies of perturba tions over such backgrounds focused exclusively on the odd-parity sector\, which yields stability conditions solely for the tensor (gravitational) m ode. Consequently\, the behavior of the scalar degree of freedom remained unconstrained. \n\nIn this work\, we address this gap by investigating the even-parity sector of perturbations in both Horndeski and Beyond Horndesk i gravity over a general time-dependent\, spherically symmetric background . By utilizing the Regge-Wheeler formalism and focusing on monopole ($\\el l=0$) perturbations\, we isolate the dynamics of the scalar degree of free dom. We successfully integrate out non-dynamical fields and derive the exp licit quadratic action for the remaining physical scalar mode. \n\nAs a ma in result\, we obtain exact no-ghost and gradient stability conditions\, a s well as the expression for the radial propagation speed of the scalar mo de. These novel constraints strictly limit the scalar sector and complemen t the previously known tensor-mode conditions from the odd sector. Togethe r\, they establish a stringent theoretical framework for the parameter spa ce of Horndeski and Beyond Horndeski theories\, which is essential for bui lding physically consistent astrophysical and cosmological models.\n\nhttp s://indico.particle.mephi.ru/event/626/contributions/6256/ LOCATION: Conference Hall 5 URL:https://indico.particle.mephi.ru/event/626/contributions/6256/ END:VEVENT BEGIN:VEVENT SUMMARY:Inhomogeneous Cosmological Bounce in Cubic Horndeski Theory DTSTART;VALUE=DATE-TIME:20261029T145500Z DTEND;VALUE=DATE-TIME:20261029T151000Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6257@cern.ch DESCRIPTION:Speakers: Marina Bakhlova (M.V. Lomonosov Moscow State Univers ity)\nThis work investigates the physical stability of cosmological bounce scenarios. As a starting point\, we consider a previously proposed bounce solution for a homogeneous and isotropic background within a subclass of Horndeski theory. In this model\, the scalar perturbation mode is non-dyna mical ("frozen")\, which allows the system to formally evade standard no-g o theorems limiting the construction of stable bounces.\n\nIn this paper\, we investigate the stability of this solution against small spatial inhom ogeneities. To this end\, we introduce a spherically symmetric dynamical m etric and a scalar field with small inhomogeneous perturbations. Based on the derived equations of motion\, we verify the stability conditions (i.e. \, the absence of ghosts and gradient instabilities) using a newly formula ted no-go theorem extended to inhomogeneous dynamical metrics.\n\nOur nume rical analysis demonstrates that introducing even arbitrarily small spatia l inhomogeneities leads to the violation of these stability conditions. We show that the scalar mode\, which remains stable and "frozen" in the stri ctly homogeneous case\, acquires dynamics upon deformation of the bounce\, inevitably triggering the development of instabilities. Consequently\, th e mechanism for evading the no-go theorem in a homogeneous background prov es to be unstable against spatial fluctuations.\n\nhttps://indico.particle .mephi.ru/event/626/contributions/6257/ LOCATION: Conference Hall 5 URL:https://indico.particle.mephi.ru/event/626/contributions/6257/ END:VEVENT BEGIN:VEVENT SUMMARY:The predictions of inflationary models modified by a non-minimal c oupling between the scalar field and curvature DTSTART;VALUE=DATE-TIME:20261029T134000Z DTEND;VALUE=DATE-TIME:20261029T135500Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6258@cern.ch DESCRIPTION:Speakers: Evgenii Dentsel (Assistant professor)\nPossible corr ections to cosmological inflation models based on scalar-tensor gravity ar e considered. The influence of non-minimal coupling between a scalar field and curvature on cosmological dynamics and parameters of cosmological per turbations is examined\, with particular emphasis on corrections arising f rom a specific parametrization of this coupling. \n\nCosmological models b ased on physically motivated scalar field potentials are analyzed for vari ous non-minimal coupling functions\, encompassing cases in which the influ ence of the coupling on both the cosmological dynamics and the evolution o f the scalar field is either significant or negligible.\n\nSpecial attenti on is devoted to estimating deviations of scalar-tensor gravity models fro m the Einstein gravity case. These deviations are assessed by applying mod ern constraints on the parameters of cosmological perturbations. To provid e a model-independent analysis of the corrections induced by non-minimal c oupling\, a classification of inflationary scenarios is introduced. This c lassification is based on the series expansion of the tensor-to-scalar rat io as a function of the spectral index of scalar perturbations. It is show n that the proposed approach incorporates well-known inflationary models a s special cases.\n\nhttps://indico.particle.mephi.ru/event/626/contributio ns/6258/ LOCATION: Conference Hall 5 URL:https://indico.particle.mephi.ru/event/626/contributions/6258/ END:VEVENT BEGIN:VEVENT SUMMARY:Stable gravity based on Ricci\, Gauss-Bonnet\, Weyl scalars for co smology and astrophysics DTSTART;VALUE=DATE-TIME:20261029T141000Z DTEND;VALUE=DATE-TIME:20261029T142500Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6259@cern.ch DESCRIPTION:Speakers: Yury Pokrovsky (National Research Center “Kurchato v Institute”\, Moscow\, 123182\, Russia)\nRicci–Gauss–Bonnet–Weyl (RGW) gravity\, based on a pure geometric Lagrangian defined by a specific combination of the Ricci (R)\, Gauss–Bonnet (G)\, and Weyl (W) scalars\ , is proposed and discussed as a potentially viable generalization of Gene ral Relativity (GR) for cosmology\, astrophysics\, and the Solar System. I n this RGW gravity\, there are no ghosts or unstable perturbations. Within the Parameterized Post-Newtonian (PPN) formalism\, it is shown that RGW g ravity has the same PPN parameter values as GR. Without the need for a cos mological constant or dark matter\, this RGW gravity agrees well with Sola r System data\, cosmological data\, and the latest data for the scalar spe ctral index and tensor-to-scalar ratio determined by the evolution of rand om metric fluctuations during the inflationary stage of the primordial Uni verse. The physics of the gravitational field arising from RGW gravity is considered in the contexts of all cosmological stages\, black holes\, supe rnovae\, neutron stars\, compact binary systems\, galaxy rotation curves\, and weak-field gravity. Finally\, RGW gravity is discussed in the context of predictions for possible new experiments.\n\nhttps://indico.particle.m ephi.ru/event/626/contributions/6259/ LOCATION: Conference Hall 5 URL:https://indico.particle.mephi.ru/event/626/contributions/6259/ END:VEVENT BEGIN:VEVENT SUMMARY:More accurate slow-roll approximations for inflation in scalar-ten sor theories DTSTART;VALUE=DATE-TIME:20261029T135500Z DTEND;VALUE=DATE-TIME:20261029T141000Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6260@cern.ch DESCRIPTION:Speakers: Maria Skugoreva ()\nWe propose new versions of the s low-roll approximation for inflationary models with nonminimally coupled s calar fields. We derive more precise expressions for the standard slow-rol l parameters as functions of the scalar field. To verify the accuracy of t he proposed approximations\, we consider inflationary models with the indu ced gravity term and the fourth-order monomial potential. For specific val ues of the model parameters\, this model is the well-known Higgs-driven in flationary model. We investigate the inflationary dynamics in the Jordan f rame and come to the conclusion that the proposed versions of the slow-rol l approximation are not only more accurate at the end of inflation\, but a lso give essentially more precise estimations for the tensor-to-scalar rat io r and the amplitude of scalar perturbations As.\n\nhttps://indico.parti cle.mephi.ru/event/626/contributions/6260/ LOCATION: Conference Hall 5 URL:https://indico.particle.mephi.ru/event/626/contributions/6260/ END:VEVENT BEGIN:VEVENT SUMMARY:Three-Point Correlation Functions and Primordial Non-Gaussianity i n Horndeski Gravity beyond Leading Order DTSTART;VALUE=DATE-TIME:20261029T142500Z DTEND;VALUE=DATE-TIME:20261029T144000Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6261@cern.ch DESCRIPTION:Speakers: Maxim Stepanov (INR RAS)\nWe investigate primordial correlation functions in a broad class of cosmological models within Hornd eski gravity whose background evolution admits a controlled slow-roll expa nsion. Using the Schwinger–Keldysh (in-in) formalism\, we derive the pri mordial three-point correlation functions in the tensor and mixed scalar –tensor sectors\, including slow-roll corrections beyond the leading-ord er approximation. In particular\, to the best of our knowledge\, our resul ts provide the first general derivation of the mixed scalar–tensor bispe ctra beyond leading order in the full Horndeski theory. We further obtain the corresponding non-linearity parameters and spectral indices\, thereby providing a systematic characterization of primordial non-Gaussianity in t his broad class of theories. We also verify the relevant Maldacena consist ency relations in the squeezed limits of the mixed correlators. Besides se rving as a nontrivial check of the calculations\, this verification establ ishes that the resulting bispectra satisfy the soft-limit constraints impl ied by residual diffeomorphism invariance and adiabatic single-clock dynam ics. As an application\, we consider a non-singular cosmological model des cribing a bouncing Universe and evaluate the associated non-linearity para meters. The resulting predictions connect the primordial dynamics of non-s ingular cosmology with potentially observable signatures of non-Gaussianit y that may be tested by future cosmological observations.\n\nhttps://indic o.particle.mephi.ru/event/626/contributions/6261/ LOCATION: Conference Hall 5 URL:https://indico.particle.mephi.ru/event/626/contributions/6261/ END:VEVENT BEGIN:VEVENT SUMMARY:Perturbative unitarity and Goldstone effective field theory in mod ified Genesis DTSTART;VALUE=DATE-TIME:20261029T152500Z DTEND;VALUE=DATE-TIME:20261029T154000Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6262@cern.ch DESCRIPTION:Speakers: Zlata Evarovskaya (Moscow State U.)\nWe develop a ma nifestly conformal-frame-independent approach to assessing perturbative un itarity and apply it to modified Genesis in a $G_2+G_3$ Horndeski model. T he construction uses an effective metric determined by the tensor quadrati c action\, its associated conformal time\, and canonically normalized scal ar perturbations. We determine the quadratic coefficients and scalar sound speed\, analyze linear stability\, and express the scalar cubic action in frame-invariant variables\, retaining interactions generated by time-depe ndent canonical normalization. Power counting identifies potentially restr ictive interactions and estimates their characteristic scales relative to the background evolution scale in the asymptotic past. \n\nWe then compute the tree-level scalar-exchange contribution to $2 \\rightarrow 2$ scatter ing in a local high-energy approximation. Explicit cancellations among the nominally leading interactions demonstrate the limitations of estimates b ased on individual operators. The retained leading exchange amplitude cont ains only the $\\ell=0$ and $\\ell=2$ partial waves\, and we evaluate thes e projections to estimate the perturbative validity range and its dependen ce on the scalar sound speed. \n\nAs a complementary description of the sc alar sector\, we derive the cubic Goldstone action for the relevant unitar y-gauge effective-field-theory operators on a fixed FLRW background\, reta ining the time dependence of their coefficients and the interactions gener ated by restoring time diffeomorphisms.\n\nhttps://indico.particle.mephi.r u/event/626/contributions/6262/ LOCATION: Conference Hall 5 URL:https://indico.particle.mephi.ru/event/626/contributions/6262/ END:VEVENT BEGIN:VEVENT SUMMARY:Problems of vacuum energy and their possible solution DTSTART;VALUE=DATE-TIME:20261029T132000Z DTEND;VALUE=DATE-TIME:20261029T134000Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6263@cern.ch DESCRIPTION:Speakers: Elena Arbuzova (Dubna State University and Novosibir sk State University)\nA dynamical mechanism for vacuum energy compensation in both de Sitter (dS) and anti-de Sitter (AdS) space-times is discussed. The proposed cosmological model relies on a non-minimal coupling between a scalar field and the curvature scalar. We demonstrate that this mechanis m efficiently eliminates huge initial vacuum energies (both positive and n egative)\, dynamically driving the curvature scalar down to zero. In both cases\, the universe enters a power-law expansion regime typical for a cos mology dominated by relativistic matter.\n\nhttps://indico.particle.mephi. ru/event/626/contributions/6263/ LOCATION: Conference Hall 5 URL:https://indico.particle.mephi.ru/event/626/contributions/6263/ END:VEVENT BEGIN:VEVENT SUMMARY:Dynamical evolution of primordial black hole clusters with lognorm al mass distribution DTSTART;VALUE=DATE-TIME:20261029T064500Z DTEND;VALUE=DATE-TIME:20261029T070000Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6248@cern.ch DESCRIPTION:Speakers: Yana Savchenko (Novosibirsk State University\, Budke r Institute of Nuclear Physics)\nBlack holes formed in the early Universe (primordial black holes\, PBHs) may simultaneously explain several astroph ysical anomalies. These include\, for example\, the existence of supermass ive black holes in the young Universe ($z>6$\, [Mazzucchelli C. et al.\, ( 2017\, ApJ)][1]) and black holes with masses of $\\sim30 M_\\odot$ detecte d by gravitational-wave observatories ([LVK Scientific Collaboration et al . 2025][2]) that fall into the “forbidden” mass gap for remnants of st ellar collapse [(Abbott R. et al. (2020b\, Phys. Rev. Lett.))][3]. PBHs ma y also contribute a fraction of the dark matter (DM)\, although for solar mass range it is already constrained by $\\leq 10\\%$ [(P. Mroz et al. (2 024\, Nature))][4].\n\nIn the basic scenario\, it is assumed that PBHs are spatially uncorrelated. However\, if PBHs are derived from large non-Gaus sian tails of density contrast\, they can be spatially clustered at birth ([Animali et al.\, (2024\, JCAP)][5]). There are other models that lead to clustering such as the modified Affleck-Dine mechanism ([Kawasaki et al.\ , (2021\, JCAP)][6]). The clustering of PBHs would change the merger histo ry of PBHs\, therefore it is important to study such systems.\n\nWe presen t a numerical study of dynamical evolution of isolated primordial black ho le clusters. We use mass distribution of PBHs derived from LIGO-Virgo-Kagr a data fit ([Dolgov et al.\, (2020\, JCAP)][7]\; [Andres-Carcasona et al. (2024\, Phys. Rev. D.)][8]). The evolution of clusters was computed using the direct N-body code $\\textbf{NBODY6++GPU}$ and takes into account orbi t-averaged gravitational wave emission. We explore how the parameters of s uch clusters affect the merger rate and masses of merging binaries.\n\n\n [1]: https://ui.adsabs.harvard.edu/link_gateway/2017ApJ...849...91M/doi:1 0.3847/1538-4357/aa9185\n [2]: https://ui.adsabs.harvard.edu/link_gateway /2025arXiv250818082T/doi:10.48550/arXiv.2508.18082\n [3]: https://doi.org /10.1103/PhysRevLett.125.101102\n [4]: https://ui.adsabs.harvard.edu/link _gateway/2024Natur.632..749M/doi:10.1038/s41586-024-07704-6\n [5]: https: //doi.org/10.48550/arXiv.2402.08642\n [6]: https://doi.org/10.48550/arXiv .2107.03580\n [7]: https://doi.org/10.1088/1475-7516/2020/12/017\n [8]: https://doi.org/10.1103/PhysRevD.110.023040\n\nhttps://indico.particle.mep hi.ru/event/626/contributions/6248/ LOCATION: Conference Hall 5 URL:https://indico.particle.mephi.ru/event/626/contributions/6248/ END:VEVENT BEGIN:VEVENT SUMMARY:Primordial black holes in chaotic in°ation with the bumped potent ial (“trampoline”) DTSTART;VALUE=DATE-TIME:20261029T063000Z DTEND;VALUE=DATE-TIME:20261029T064500Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6250@cern.ch DESCRIPTION:Speakers: Alexander Melikhov (Institute for Nuclear Research o f the Russian Academy of Sciences)\nPrimordial black hole (PBH) production is investigated in a chaotic inflation model with a massive inflaton whos e potential $V_0 + m^2\\varphi^2/2$ contains a localized bump. The presenc e of the bump temporarily slows down the inflaton motion and leads to high \, narrow peaks in the density perturbation spectrum. The density perturba tion spectrum and the resulting PBH mass function are calculated numerical ly\, showing that the model can produce PBHs with characteristic masses ar ound $10^{20}$ g.\n\nConstraints on the PBH abundance arising from Hawking radiation and its heating of interstellar dust are further studied. The o btained PBH mass spectrum is approximated by a parabolic distribution\, al lowing the dependence of the constraints on the width of the mass function to be investigated. Both a homogeneous cosmological PBH distribution and a Navarro–Frenk–White Galactic halo distribution are considered. The r esulting constraints are found to depend strongly on the width of the PBH mass function: broader mass functions are subject to substantially stronge r constraints\, while narrow mass functions around $10^{20}$ g can still a llow a significant PBH contribution to dark matter.\n\nhttps://indico.part icle.mephi.ru/event/626/contributions/6250/ LOCATION: Conference Hall 5 URL:https://indico.particle.mephi.ru/event/626/contributions/6250/ END:VEVENT BEGIN:VEVENT SUMMARY:The possibility of observing primordial black holes with hydrogen subordinate lines DTSTART;VALUE=DATE-TIME:20261029T061000Z DTEND;VALUE=DATE-TIME:20261029T063000Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6251@cern.ch DESCRIPTION:Speakers: Yury Eroshenko (INR RAS)\nThe formation of spectral- spatial distortions of cosmic microwave background radiation near primordi al black holes at redshifts 100-1000 is considered. After hydrogen recombi nation\, the radiation from these objects leads to the significant increas e in the population of the hydrogen subordinate levels in their surroundin g environment. Consequently\, this allows for the observation of a Fraunho fer-like absorption spectrum in the cosmic microwave background. These sub ordinate hydrogen lines currently lie in the radio wavelength range. Оne should observe circular absorption or emission features around the objects with small angular sizes.\n\nhttps://indico.particle.mephi.ru/event/626/c ontributions/6251/ LOCATION: Conference Hall 5 URL:https://indico.particle.mephi.ru/event/626/contributions/6251/ END:VEVENT BEGIN:VEVENT SUMMARY:Gravitational-wave signatures of primordial black hole clustering DTSTART;VALUE=DATE-TIME:20261029T070000Z DTEND;VALUE=DATE-TIME:20261029T071500Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6252@cern.ch DESCRIPTION:Speakers: Viktor Stasenko ()\nThis work examines the impact of primordial black hole clustering on the dynamics of their mergers. Gravit ational perturbations from neighboring black holes within a cluster pertur b the orbital parameters of binary systems\, effectively excluding them fr om the population of merging binaries. This\, in turn\, characteristically alters the merger history compared to the non-clustered case\, which mani fests both in the redshift evolution of the merger rate and in the spectru m of the stochastic gravitational-wave background. We discuss how these ef fects can be tested by future gravitational-wave observations.\n\nhttps:// indico.particle.mephi.ru/event/626/contributions/6252/ LOCATION: Conference Hall 5 URL:https://indico.particle.mephi.ru/event/626/contributions/6252/ END:VEVENT BEGIN:VEVENT SUMMARY:Direct surface-based simulation of primordial black hole clusters formation via collapse of non-spherical domain walls DTSTART;VALUE=DATE-TIME:20261029T071500Z DTEND;VALUE=DATE-TIME:20261029T073000Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6253@cern.ch DESCRIPTION:Speakers: Ivan Letyagin (MEPhI)\nOne possible mechanism for th e formation of primordial black holes (PBHs) \nis the collapse of domain w alls. Previous theoretical models considered PBH \nformation in the spheri cal approximation\, whereas full field-theoretic \nsimulations of non-sphe rical domain walls clusters are too computationally \ndemanding to accumul ate sufficient statistics.\n\nIn this work\, we derive the equations of mo tion of a domain wall in the \nthin-wall approximation and propose a numer ical method for evolving the \nwall surface using triangular mesh algorith ms. For prescribed field configurations of a cluster\, the method yields the differential mass spectrum of the resulting PBHs.\n\nBased on a Monte Carlo ensemble\, we obtain $dN/dM \\propto M^{-\\alpha}$ \nwith $\\alpha = 2.31^{+0.01}_{-0.02}$\, significantly larger than the \ntheoretical value $\\alpha \\approx 1.75$ for spherical-wall collapse\, \nindicating a larg er fraction of low-mass PBHs. This deviation is \npresumably due to the fr agmentation of walls with complex geometry\, which is absent \nin the sphe rical approximation.\n\nhttps://indico.particle.mephi.ru/event/626/contrib utions/6253/ LOCATION: Conference Hall 5 URL:https://indico.particle.mephi.ru/event/626/contributions/6253/ END:VEVENT BEGIN:VEVENT SUMMARY:Investigation of gravitational wave background from the domain wal ls in the early universe using pulsar timing arrays DTSTART;VALUE=DATE-TIME:20261029T074500Z DTEND;VALUE=DATE-TIME:20261029T080000Z DTSTAMP;VALUE=DATE-TIME:20261102T000239Z UID:indico-contribution-318-6254@cern.ch DESCRIPTION:Speakers: Alexey Chugainov ()\nHigh-precision measurements of pulsar timing arrays (PTA) allow us to probe stochastic gravitational wave background (GWB)\, which is generated by various processes in the Univers e. Domain walls (DWs) that emerged in the early Universe could be one of t he hypothetical sources of such GWB. In this work\, two different models o f DWs are considered. Such objects produce GWB with a distinctive power sp ectrum. In this work we develop an algorithm to search for such signals in PTA datasets. The algorithm has been validated on a simulated pulsar timi ng data. We apply the analysis scheme on the latest data release of the Eu ropean Pulsar Timing Array collaboration (EPTA). We present obtained estim ates and constraints on physical parameters\, which describe the evolution of melting DWs and biased DWs.\n\nhttps://indico.particle.mephi.ru/event/ 626/contributions/6254/ LOCATION: Conference Hall 5 URL:https://indico.particle.mephi.ru/event/626/contributions/6254/ END:VEVENT END:VCALENDAR