BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Production of dijets with large rapidity separation at colliders DTSTART;VALUE=DATE-TIME:20201007T093000Z DTEND;VALUE=DATE-TIME:20201007T094500Z DTSTAMP;VALUE=DATE-TIME:20260421T234145Z UID:indico-contribution-176-2370@cern.ch DESCRIPTION:Speakers: Anatolii Egorov (Petersburg Nuclear Physics Institut e NRC Kurchatov Institute & Peter the Great St. Petersburg Polytechnic Un iversity)\nProduction of dijets with large rapidity separation at collider s in\nmodified logarithm approximations is considered.\nThe results for re summations of different type of logarithms:\nsoft-gluon\, non-global and S udakov ones are obtained.\nThe results for various dijet observables are c onfronted with LHC data.\n\nhttps://indico.particle.mephi.ru/event/35/cont ributions/2370/ LOCATION:Zoom HEP Theory URL:https://indico.particle.mephi.ru/event/35/contributions/2370/ END:VEVENT BEGIN:VEVENT SUMMARY:Finding new physics\, phenomenological\, experimental and astrophy sical predictions DTSTART;VALUE=DATE-TIME:20201007T091500Z DTEND;VALUE=DATE-TIME:20201007T093000Z DTSTAMP;VALUE=DATE-TIME:20260421T234145Z UID:indico-contribution-176-2154@cern.ch DESCRIPTION:Speakers: Chitta Ranjan Das (BLTP\, JINR\, Dubna\, Russia)\nTh e crucial phenomenological and experimental predictions for new physics ar e outlined\, where the number of problems of the Standard Model (neutrino masses and oscillations\, dark matter\, baryon asymmetry of the Universe\, strong CP-problem) could find their solutions.\n\nThe analogies between t he Cosmological time evolution of the early universe and multiparticle pro duction in high-energy collisions are discussed and the search for new phy sics and phenomena.\n\nhttps://indico.particle.mephi.ru/event/35/contribut ions/2154/ LOCATION:Zoom HEP Theory URL:https://indico.particle.mephi.ru/event/35/contributions/2154/ END:VEVENT BEGIN:VEVENT SUMMARY:Charmonia Production in W -> c c Ds Decays DTSTART;VALUE=DATE-TIME:20201007T084500Z DTEND;VALUE=DATE-TIME:20201007T090000Z DTSTAMP;VALUE=DATE-TIME:20260421T234145Z UID:indico-contribution-176-2160@cern.ch DESCRIPTION:Speakers: Alexey Luchinsky (Institute for High Energy Physics) \nIn the presented paper production of charmonium state $\\mathcal{Q}$ in exclusive $W\\to\\mathcal{Q} D_s^{(*)}$ decays is analyzed in the framewo rk of both leading order Nonrelativistic Quantum Chromodynamics (NRQCD) an d light-cone expansion (LC) models. Analytical and numerical predictions f or the branching fractions of these decays in both approaches are given. T he typical value of the branching fractions is $\\sim 10^{-11}$ and it tur ns out that the LC results are about 4 times lager than NRQCD ones\, so th e effect of internal quark should be taken into account. Some estimates of color-octet contributions are presented and it is shown\, that these cont ributions could be comparable with color-singlet results.\n\nhttps://indic o.particle.mephi.ru/event/35/contributions/2160/ LOCATION:Zoom HEP Theory URL:https://indico.particle.mephi.ru/event/35/contributions/2160/ END:VEVENT BEGIN:VEVENT SUMMARY:On mass limits for scalar color octet from the LHC data on tttt an d tbtb production. DTSTART;VALUE=DATE-TIME:20201007T090000Z DTEND;VALUE=DATE-TIME:20201007T091500Z DTSTAMP;VALUE=DATE-TIME:20260421T234145Z UID:indico-contribution-176-2136@cern.ch DESCRIPTION:Speakers: Mikhail Martynov (Yaroslavl P.G.Demidov State Univer sity)\nThe contributions to the cross sections ${ t\\bar{t} t\\bar{t}}$ a nd $t\\bar{t}b\\bar{b}$ production at the LHC from color scalar octets (sc alar gluons) $F_a$ predicted by the minimal model with four color quark-le pton symmetry are calculated. \nFrom current LHC data on total cross secti on of $ t\\bar{t}t\\bar{t}$ and $t\\bar{t}b\\bar{b}$ production we found the mass limits on color scalar octets $F_a$.\n\nhttps://indico.particle. mephi.ru/event/35/contributions/2136/ LOCATION:Zoom HEP Theory URL:https://indico.particle.mephi.ru/event/35/contributions/2136/ END:VEVENT BEGIN:VEVENT SUMMARY:QCD corrections for double charmonia production in $e^+e^-$ annihi lation DTSTART;VALUE=DATE-TIME:20201007T083000Z DTEND;VALUE=DATE-TIME:20201007T084500Z DTSTAMP;VALUE=DATE-TIME:20260421T234145Z UID:indico-contribution-176-2155@cern.ch DESCRIPTION:Speakers: Ilia Belov ()\nWe discuss $J/\\psi\\ \\eta_c$ produc tion in $e^+e^-$ annihilation at NLO. We are focusing at virtual $Z_0$ con tribution into this process. Cross-sections behavior at high energies will be performed.\n\nhttps://indico.particle.mephi.ru/event/35/contributions/ 2155/ LOCATION:Zoom HEP Theory URL:https://indico.particle.mephi.ru/event/35/contributions/2155/ END:VEVENT BEGIN:VEVENT SUMMARY:D wave Bc production at LHC DTSTART;VALUE=DATE-TIME:20201007T081500Z DTEND;VALUE=DATE-TIME:20201007T083000Z DTSTAMP;VALUE=DATE-TIME:20260421T234145Z UID:indico-contribution-176-2157@cern.ch DESCRIPTION:Speakers: Aleksandr Berezhnoi (SINP MSU)\nThe production cross section value of $D$ wave states of $B_c$ meson is estimated for LHC expe riments. The observation perspectives of such states at LHC experiments ar e discussed.\n\nhttps://indico.particle.mephi.ru/event/35/contributions/21 57/ LOCATION:Zoom HEP Theory URL:https://indico.particle.mephi.ru/event/35/contributions/2157/ END:VEVENT BEGIN:VEVENT SUMMARY:Light-Cone Distribution Amplitudes of Doubly-Heavy Baryons DTSTART;VALUE=DATE-TIME:20201007T080000Z DTEND;VALUE=DATE-TIME:20201007T081500Z DTSTAMP;VALUE=DATE-TIME:20260421T234145Z UID:indico-contribution-176-2138@cern.ch DESCRIPTION:Speakers: Alisa Shukhtina ()\nDoubly-heavy baryons\, whose dyn amics is determined by a light quark sutuated in a color field of a static pair of heavy quarks\, are investigated. Non-local interpolation currents are introduced and corresponding matrix elements between the baryon and v acuum state are expressed in terms of light-cone distribution amplitudes. Model functions for baryon distribution amplitudes are suggested and their scale dependence is studied in the pertubative QCD framework. The similar ity between the heavy meson and doubly-heavy baryon disribution amplitudes is discussed.\n\nhttps://indico.particle.mephi.ru/event/35/contributions/ 2138/ LOCATION:Zoom HEP Theory URL:https://indico.particle.mephi.ru/event/35/contributions/2138/ END:VEVENT BEGIN:VEVENT SUMMARY:Energy levels in three-particle muonic ions (µ e Li)\, (µ e Be)\ , (µ e B) DTSTART;VALUE=DATE-TIME:20201006T150500Z DTEND;VALUE=DATE-TIME:20201006T152000Z DTSTAMP;VALUE=DATE-TIME:20260421T234145Z UID:indico-contribution-176-2153@cern.ch DESCRIPTION:Speakers: Alexey Eskin ()\nCoulomb systems of three particles\ , consisting of an electron\, a negative muon and a nucleus\, are of signi ficant interest in many areas of physics\, including atomic spectroscopy a nd quantum electrodynamics. The ions of muonic lithium (µ e Li)\, berylli um (µ e Be)\, and boron (µ e B) include the simplest light nuclei behind hydrogen and helium. The lifetime of such ions is determined by the lifet ime of the negative muon. These bound states have a complex energy structu re\, which arises as a result of the Coulomb interaction of particles\, as well as the interaction of their magnetic moments. The interest in these systems is due to the fact that the composite particles in them have very different masses. As a result\, the muon and the nucleus form a quasi-nucl eus around which the electron moves\, and the three-particle system itself looks\, in the first approximation\, like a two-particle atom. The electr onic excited states 2S and 2P in such atoms can be investigated experiment ally. In any case\, such a program already exists for the muonic helium at om (µ e He). To calculate the energy levels in three-particle systems\, i n this work\, we use the stochastic variational method\, which has proven itself in the study of hydrogen mesomolecules.\n\nhttps://indico.particle. mephi.ru/event/35/contributions/2153/ LOCATION:Zoom HEP Theory URL:https://indico.particle.mephi.ru/event/35/contributions/2153/ END:VEVENT BEGIN:VEVENT SUMMARY:Hyperfine structure of excited states of hydrogen mesomolecules DTSTART;VALUE=DATE-TIME:20201006T153500Z DTEND;VALUE=DATE-TIME:20201006T155000Z DTSTAMP;VALUE=DATE-TIME:20260421T234145Z UID:indico-contribution-176-2152@cern.ch DESCRIPTION:Speakers: Viacheslav Sorokin (Samara University)\nThe hyperfin e structure of excited states of muonic molecules tdμ\, tpμ and dpμ is calculated on the basis of stochastic variational method. The basis wave f unctions are taken in the Gaussian form. All matrix elements of the Hamilt onian are calculated analytically. For numerical calculation\, a computer code is written in the MATLAB system. Numerical values of hyperfine splitt ing of excited states in hydrogen mesomolecules tdμ\, tpμ and dpμ are o btained.\n\nhttps://indico.particle.mephi.ru/event/35/contributions/2152/ LOCATION:Zoom HEP Theory URL:https://indico.particle.mephi.ru/event/35/contributions/2152/ END:VEVENT BEGIN:VEVENT SUMMARY:Energy interval (1S-2S) in muonic ions of lithium\, beryllium and boron DTSTART;VALUE=DATE-TIME:20201006T152000Z DTEND;VALUE=DATE-TIME:20201006T153500Z DTSTAMP;VALUE=DATE-TIME:20260421T234145Z UID:indico-contribution-176-2151@cern.ch DESCRIPTION:Speakers: Alexei Martynenko (Samara U.)\nIn the framework of t he quasipotential method in quantum electrodynamics\, the energy interval (1S-2S) in muonic ions of lithium\, beryllium and boron is calculated. We take into account corrections of fifth and sixth orders in fine structur e constant\, which are determined by relativistic effects\, the effects of vacuum polarization\, nuclear structure and recoil\, as well as combined corrections including listed. Nuclear structure effects are expressed in t erms of the charge radius of the nuclei in the case of one-photon interact ion and the electromagnetic form factors of the nuclei in the case of two- photon interaction. The obtained numerical values of the energy interval ( 1S-2S) can be used for a comparison with future experimental data and for more accurate determination of the nucleus charge radii.\n\nhttps://indico .particle.mephi.ru/event/35/contributions/2151/ LOCATION:Zoom HEP Theory URL:https://indico.particle.mephi.ru/event/35/contributions/2151/ END:VEVENT BEGIN:VEVENT SUMMARY:The lack of vacuum polarization in quantum electrodynamics with sp inors in fermion equations DTSTART;VALUE=DATE-TIME:20201006T145000Z DTEND;VALUE=DATE-TIME:20201006T150500Z DTSTAMP;VALUE=DATE-TIME:20260421T234145Z UID:indico-contribution-176-2162@cern.ch DESCRIPTION:Speakers: Vasily Neznamov (Russian Federal Nuclear Center - Al l-Russian Research Institute of Experimental Physics (Sarov))\nThe variant s of quantum electrodynamics (QED) with spinors in fermion equations are b riefly examined. In the new variants of the theory\, there is no necessity in the concept of vacuum polarization. The new content of fermion vacuum (without the Dirac sea) in the examined QED variants leads to new physical consequences\, part of which can be tested experimentally in the future.\ n\nhttps://indico.particle.mephi.ru/event/35/contributions/2162/ LOCATION:Zoom HEP Theory URL:https://indico.particle.mephi.ru/event/35/contributions/2162/ END:VEVENT BEGIN:VEVENT SUMMARY:Determination of the proton charge radius from the study of the hy drogen S-energy levels DTSTART;VALUE=DATE-TIME:20201006T143500Z DTEND;VALUE=DATE-TIME:20201006T145000Z DTSTAMP;VALUE=DATE-TIME:20260421T234145Z UID:indico-contribution-176-2137@cern.ch DESCRIPTION:Speakers: Fedor Martynenko ()\nAt present\, four complementary methods are used to obtain the charge radii of light nuclei: an elastic s cattering of electrons by nuclei\, elastic scattering of muons by nuclei\, spectroscopy of electron atoms\, and high-precision laser spectroscopy in muonic atoms. Traditionally\, elastic electron scattering was the first m ethod to determine the internal structure of a proton. Elastic scattering of leptons by a target nucleus is described by form factors included in th e theoretical expression for the scattering cross-section. A proton or oth er light nucleus is a compound particle\, and its size is determined by th e charge radius. It is related to the slope of the electric form factor of the proton $ G_{pE} (q) $ at $ q^2 = 0 $. Over the past two decades\, ato mic laser spectroscopy has proven to be a powerful tool for determining th e charge radii of light nuclei. Atomic spectroscopy of hydrogen is an indi rect way of determining the charge radius $ r_{pE} $ of a proton from pres ision measurements of certain energy intervals. While electron scattering and spectroscopy of electron atoms have been available for a long time\, m uon spectroscopy became available only in 2010 due to the work of the CREM A collaboration. As a result of the first CREMA experiments in 2010\, the value $ r_{pE} = 0.84184 (67) $ fm was obtained\, which was 10 times more accurate than all previous values from experiments with electronic systems . Moreover\, this value was significantly less than the CODATA value\, $ r _{pE} = 0.8768 (69) $ fm. This difference is called the "puzzle" of the pr oton radius. In this work\, a precision study of the structure of energy l evels of S-states of hydrogen in quantum electrodynamics is carried out ta king into account corrections for vacuum polarization\, nuclear structure\ , relativism\, as well as complex combined corrections that include the ab ove. The frequency of the transition between the levels of S-states is cal culated\, which is necessary for comparison with the corresponding experim ental data.\n\nhttps://indico.particle.mephi.ru/event/35/contributions/213 7/ LOCATION:Zoom HEP Theory URL:https://indico.particle.mephi.ru/event/35/contributions/2137/ END:VEVENT BEGIN:VEVENT SUMMARY:The Nambu Sum Rule in the Composite Two Higgs Doublet Model DTSTART;VALUE=DATE-TIME:20201006T140500Z DTEND;VALUE=DATE-TIME:20201006T142000Z DTSTAMP;VALUE=DATE-TIME:20260421T234145Z UID:indico-contribution-176-2161@cern.ch DESCRIPTION:Speakers: Mahmoud Khalifa (Moscow Institute of Physics and Tec hnology\, Dolgoprudnyi\, Moscow oblast\, 141701 Russia\, Department of Phy sics\, Al-Azhar University\, Cairo\, 11751 Egypt)\nThe spectrum of spinles s modes in a model with the 〖SU(2)〗_L×〖SU(2)〗_R symmetrical four -quark interaction proposed by Miransky\, Tanabashi\, and Yamawaki is stud ied. For the sake of simplicity\, only four-fermion interactions of top an d bottom quarks are considered. The spinless modes result from spontaneous electroweak interaction symmetry breaking and are coupled quark–antiqua rk states associated with SU(2) two Higgs doublets. Their dynamics is desc ribed by the effective Lagrangian obtained by the Schwinger– DeWitt meth od. The spectrum is represented by excitations of five types\, the mass of each being expressed by the parameters of the model. It is shown that the model yields phenomenologically acceptable values of both the mass of qua rks m_t=173 GeV and m_b=4.18 GeV and the mass of the standard Higgs state m_(χ_1 )=125 GeV. The masses of the particles that comprise the second Hi ggs doublet m_(h^∓ )=275 GeV\, m_(χ_1 )=325 GeV and m_(ϕ_0 )=125 GeV\, have been calculated. The Nambu sum rule and the conditions for satisfyin g it in the theories with the broken 〖U(1)〗_A symmetry are discussed.\ n\nhttps://indico.particle.mephi.ru/event/35/contributions/2161/ LOCATION:Zoom HEP Theory URL:https://indico.particle.mephi.ru/event/35/contributions/2161/ END:VEVENT BEGIN:VEVENT SUMMARY:On perturbative unitarity in an extended MSSM Higgs sector DTSTART;VALUE=DATE-TIME:20201006T142000Z DTEND;VALUE=DATE-TIME:20201006T143500Z DTSTAMP;VALUE=DATE-TIME:20260421T234145Z UID:indico-contribution-176-2150@cern.ch DESCRIPTION:Speakers: Elena Fedotova (SINP MSU)\nThe MSSM Higgs sector ext ended by dimension-six operators $U^{(6)}$ [1]\, which are loop contributi ons in a Coleman-Weinberg-type potential\, is considered. The presence of such additional contributions allows reopening phenomenological MSSM scena rios [2] closed in previous analyses.\nIn order to restrict corresponding parameter space\, perturbative unitarity constraints must be satisfied.\nT he common approach for checking this is to consider a two-particle scatter ing\nmatrix of scalars in the large center-of-mass energy $\\sqrt{s}$ limi t where only point interactions contribute [3].\nHowever\, due to SUSY-par ticles interactions in MSSM\,\ntrilinear couplings can be significant and\ n large contributions are present\nat smaller $\\sqrt{s}$ [4].\nWe find th e analytical formula for quartic and cubic couplings for the Higgs potenti al extended by dimension-six operators\,\ncompare results with loop correc ted constraints\, which use the large $\\sqrt{s}$ approximation with and w ithout additional $U^{(6)}$-contributions\, and\nshow how the allowed regi ons in the parameter space are affected in these cases.\n\n1. M. N. Dubini n and E. Yu. Petrova\, Phys. Rev. D 95\, 055021 (2017). \n2. M. N. Dubinin and E. Yu. Petrova\, Int. J. Mod. Phys. A 33\, 1850150 (2018)\; 1908.0522 3 [hep-ph].\n3. B. W. Lee\, C. Quigg\, and H. B. Thacker\, Phys. Rev. D 16 \, 1519 (1977)\; I. F. Ginzburg and I. P. Ivanov\, Phys. Rev. D 72\, 11501 0 (2005)\; A. G. Akeroyd\, A. Arhrib\, and E. Naimi\, Phys. Lett. B 490\, 119 (2000).\n4. M. D. Goodsell and F. Staub\, Eur. Phys. J. C 78\, 649 (20 18)\; M. E. Krauss and F. Staub\, Phys.Rev. D98\, no.1\, 015041 (2018).\n\ nhttps://indico.particle.mephi.ru/event/35/contributions/2150/ LOCATION:Zoom HEP Theory URL:https://indico.particle.mephi.ru/event/35/contributions/2150/ END:VEVENT BEGIN:VEVENT SUMMARY:Analytic reconstruction of pp elastic scattering amplitudes from t he complete sets of experiments at the SPASCHARM facility at U70. DTSTART;VALUE=DATE-TIME:20201006T091500Z DTEND;VALUE=DATE-TIME:20201006T093000Z DTSTAMP;VALUE=DATE-TIME:20260421T234145Z UID:indico-contribution-176-2156@cern.ch DESCRIPTION:Speakers: M.B. Nurusheva ()\nThe direct reconstruction of the pp elastic scattering amplitudes at the energy of 16 GeV is discussed. At the SPASCHARM experiment\, the 19 different spin dependent observables wi ll be measured in pp elastic scattering. The suggested selection of observ ables allows a complete and unique analytical reconstruction of elastic sc attering amplitudes as a solution of the system of bilinear equations. A s et of physical observables\, which are necessary for modeless reconstructi on of all five complex elastic pp scattering amplitudes\, is defined.\n\nh ttps://indico.particle.mephi.ru/event/35/contributions/2156/ LOCATION:Zoom HEP Theory URL:https://indico.particle.mephi.ru/event/35/contributions/2156/ END:VEVENT BEGIN:VEVENT SUMMARY:Spin-spin correlations between quark and a spin-$\\frac{1}{2}$ com posite system DTSTART;VALUE=DATE-TIME:20201006T090000Z DTEND;VALUE=DATE-TIME:20201006T091500Z DTSTAMP;VALUE=DATE-TIME:20260421T234145Z UID:indico-contribution-176-2158@cern.ch DESCRIPTION:Speakers: Harleen Dahiya (Dr. B.R. Ambedkar National Institute of Technology\, Jalandhar)\nWe study the correlation between the fermion composite system and quark spins by using the light-cone quark-diquark mod el. We do the calculations for $u$-quark and $d$-quark in the fermion syst em by considering different polarization configrations of both. The contri bution from scalar and axial-vector diquarks is taken into account. The ov erlap representation of light-front wavefunctions is used for the calculat ions. The spin-spin correlations for $u$ and $d$ quarks are presented in t ransverse impact-parameter plane and transverse momentum plane as well.\n\ nhttps://indico.particle.mephi.ru/event/35/contributions/2158/ LOCATION:Zoom HEP Theory URL:https://indico.particle.mephi.ru/event/35/contributions/2158/ END:VEVENT BEGIN:VEVENT SUMMARY:Strange Quark Matter with $\\beta$-equilibrium condition DTSTART;VALUE=DATE-TIME:20201006T084500Z DTEND;VALUE=DATE-TIME:20201006T090000Z DTSTAMP;VALUE=DATE-TIME:20260421T234145Z UID:indico-contribution-176-2159@cern.ch DESCRIPTION:Speakers: MANISHA KUMARI (Dr. B. R. Ambedkar National Institut e of Technology\, Jalandhar)\nThe present study explores the properties of strange quark matter (SQM) or strange quark star (SQS) within the Polyako v extended chiral $\\text{SU(3)}$ quark mean field (PCQMF) model. Using $\ \beta$- equilibrium condition in the PCQMF model\, the analysis of effecti ve quark masses\, effective quark chemical potential\, and equation of sta te for strange quark matter at different values of vector coupling constan t is carried out. Three different conditions of Proto-Quark Star (PQS) alo ng the star evolution ($S/n_B=1\, Y_l=0.4\;~S/n_B=2\, Y_{\\nu_l}=0\;~S/n_B =0\, Y_{\\nu_l}=0$) are considered to performed the theoretical simulation . Providing a significant vector coupling constant\, the change in effecti ve quark masses with baryon density is found to be less as compared to zer o vector interaction. Further\, pressure density shows monotonically and s moothly increasing with the increase in energy density. The study thus car ried out\, anticipated to give a better insight into the role that the sup erdense matter created in heavy-ion collision experiments plays an importa nt role in understanding the properties of matter inside the core of super massive stars in the universe.\n\nhttps://indico.particle.mephi.ru/event/3 5/contributions/2159/ LOCATION:Zoom HEP Theory URL:https://indico.particle.mephi.ru/event/35/contributions/2159/ END:VEVENT BEGIN:VEVENT SUMMARY:Equivalent photons approximation: survival factor DTSTART;VALUE=DATE-TIME:20201006T081500Z DTEND;VALUE=DATE-TIME:20201006T083000Z DTSTAMP;VALUE=DATE-TIME:20260421T234145Z UID:indico-contribution-176-2140@cern.ch DESCRIPTION:Speakers: Evgenii Zhemchugov (LPI\, MEPhI)\nIn a large fractio n of collisions at the Large Hadron Collider (LHC)\, the colliding particl es miss each other and collide with their electromagnetic fields. If the p articles remain intact after such collision\, the collision is called ultr aperipheral (UPC). In the equivalent photons approximation\, the electroma gnetic field of an ultrarelativistic particle can be represented as a bunc h of real photons distributed according to a known spectrum $n(\\omega)$. This allows treatment of UPCs as photon-photon collisions\, and the Large Hadron Collider as a photon-photon collider. The photon-photon luminosity can be calculated as\n\n$\n \\frac{\\mathrm{d} L_0}{\\mathrm{d} s}\n = \\int\\limits_0^\\infty \\frac{\\mathrm{d} x}{8 x}\n n \\left( \\sqrt{\ \frac{sx}{4}} \\right)\n n \\left( \\sqrt{\\frac{s}{4x}} \\right)\n$\n\ n(assuming that the colliding particles are identical)\, where $s = 4 \\om ega_1 \\omega_2$ ($\\sqrt{s}$ is the invariant mass of the photons)\, $x = \\omega_1 / \\omega_2$ ($x$ is related to the pseudorapidity of the syste m produced)\, $\\omega_1$ and $\\omega_2$ are the photons energies.\n\nTo take into account finite sizes of the colliding particles\, the dependence on the transverse distance to the particle $b$ has to be introduced into the spectrum:\n\n$\n n(\\omega) = \\int \\mathrm{d}^2 b \\\, n(b\, \\omeg a).\n$\n\nThe photon-photon luminosity is then\n\n$\n \\frac{\\mathrm{d} L}{\\mathrm{d} s}\n = \\int\\limits_0^\\infty \\frac{\\mathrm{d} x}{8 x}\ n \\int\\mathrm{d}^2 b_1\n \\int\\mathrm{d}^2 b_2\n \\\, \n n \\left( b_1\, \\sqrt{\\frac{sx}{4}} \\right)\n n \\left( b_2\, \\sqrt{\ \frac{s}{4x}} \\right)\n P(|\\vec b_2 - \\vec b_1|)\n$\n\nwhere $P(b)$ is the probability for the particles to survive after the collision with t he impact parameter $b$. The ratio of the luminosities\,\n\n$\n S = \\fra c{\\mathrm{d} L / \\mathrm{d} s}{\\mathrm{d} L_0 / \\mathrm{d} s}\,\n$\n\n is called the survival factor\, and it describes the diminishing of the cr oss section of the ultraperipheral collision due to the disintegration of the colliding particles.\n\nIn the talk\, survival factors for the proton- proton and lead-lead collisions at the LHC are presented in a wide range o f $s$. Calculations with and without the survival factor taken into accoun t are compared to the measurements of the cross section for muon pair prod uction in UPCs (low $s$). Effects of the survival factor on the production of heavy charged particles are discussed. In the case of lead ions\, sign ificant disagreement between the two currently available sources of data o n $^{208}$Pb electromagnetic form factors is revealed.\n\nhttps://indico.p article.mephi.ru/event/35/contributions/2140/ LOCATION:Zoom HEP Theory URL:https://indico.particle.mephi.ru/event/35/contributions/2140/ END:VEVENT BEGIN:VEVENT SUMMARY:The strongly intensive observable in pp collisions at LHC energies in the string fusion model DTSTART;VALUE=DATE-TIME:20201006T083000Z DTEND;VALUE=DATE-TIME:20201006T084500Z DTSTAMP;VALUE=DATE-TIME:20260421T234145Z UID:indico-contribution-176-2139@cern.ch DESCRIPTION:Speakers: Vladimir Vechernin (St. Petersburg State University) \nThe properties of the strongly intensive variable [1] characterizing cor relations between the number of particles produced in two observation wind ows separated by a rapidity interval [2] in pp interactions at LHC energie s are studied in the framework of the string fusion model [3]. The effects of the string fusion are taken into account by introducing a finite latti ce (a grid) in the impact parameter plane [4]. The analytical calculations are supplemented by the MC simulations permitting to take into account th e experimental conditions of pp collisions in ALICE at LHC. \n\nAs a resul t\, the dependence of this variable both on the width of the observation w indows and on the value of the gap between them was found for several init ial energies. It is demonstrated that in pp collisions at LHC energies the string fusion effects have a significant impact on the behavior of this s trongly intensive variable. At that the role of these effects is increasin g with the initial energy and centrality of the collision. \n\nWe show tha t the comparison of our model results with the preliminary experimental va lues of the strongly intensive variable obtained by the analysis of the AL ICE data on pp collisions at 0.9 and 7 TeV enables to extract information on the parameters characterizing clusters with different numbers of merged strings\, in particular\, to find their two-particle correlation function s and the average multiplicity of charged particles from cluster decays.\n \nThis research was funded by the Russian Foundation for Basic Research\, project number 18-02-40075.\n\nReferences\n\n1. M.I. Gorenstein\, M. Gazdz icki\, Strongly intensive quantities\, Phys. Rev. C 84 (2011) 014904. \n2. E. Andronov\, V. Vechernin\, Strongly intensive observable between multip licities in two acceptance windows in a string model\, Eur. Phys. J. A 55 (2019) 14. \n3. M.A. Braun\, C. Pajares\, A probabilistic model of interac ting strings\, Nucl. Phys. B 390 (1993) 542. \n4. S.N. Belokurova\, V.V. V echernin\, Strongly intensive variables and long-range correlations in the model with a lattice in the transverse plane\, Theor. Math. Phys. 200 (20 19) 1094.\n\nhttps://indico.particle.mephi.ru/event/35/contributions/2139/ LOCATION:Zoom HEP Theory URL:https://indico.particle.mephi.ru/event/35/contributions/2139/ END:VEVENT BEGIN:VEVENT SUMMARY:Vector mesons spectrum in a medium with a chiral imbalance induced by the vacuum of fermions DTSTART;VALUE=DATE-TIME:20201006T080000Z DTEND;VALUE=DATE-TIME:20201006T081500Z DTSTAMP;VALUE=DATE-TIME:20260421T234145Z UID:indico-contribution-176-2163@cern.ch DESCRIPTION:Speakers: Vladimir Kovalenko (Saint Petersburg State Universit y)\nThe chiral imbalance defined as a difference between the numbers of RH and LH quarks may occur in the fireball after a heavy-ion collision at hi gh energy. It can lead to the formation of a local parity breaking LPB in a quark-hadron medium and adiabatically characterized by a topological cha rge and\, accordingly\, a topological (chiral) chemical potential $\\mu_5$ . In the field theory\, it can be considered as a time-like axial-vector $ b_\\mu$ coupled to a fermion field with its zero component associated with $\\mu_5$. The consistent way for the construction of the Lagrangian in th e presence of constant axial-vector background has been obtained in [1\, 2 ] for QED theory.\n\nIn this report\, for the description of the propertie s of light vector mesons in the presence of LPB in a fireball\, the vector -meson dominance model is applied in the lightest SU(2) sector. Employing the approach\, developed in [1\, 2]\, to the vector $\\rho$ and $\\omega$ mesons\, we obtain the mass spectrum as a function of momentum and chiral chemical potential $\\mu_5$. We show that in addition to the Chern–Simon s term [3]\, splitting the transverse polarisations of the mesons\, there is an additional contribution that becomes important at momentum and $\\mu _5$ around a few hundred MeV.\n\n\nReferences:\n\n[1] J. Alfaro\, A. Andri anov\, M. Cambiaso\, P. Giacconi and R. Soldati\, Phys. Lett. B 639\, 586- 590 (2006)\, arXiv:hep-th/0604164 [hep-th].\n\n[2] J. Alfaro\, A. Andriano v\, M. Cambiaso\, P. Giacconi and R. Soldati\, Int. J. Mod. Phys. A 25\, 3 271-3306 (2010)\, arXiv:0904.3557 [hep-th].\n\n[3] A. Andrianov\, V. Andri anov\, D. Espriu and X. Planells\, Phys. Lett. B 710\, 230-235 (2012)\, ar Xiv:1201.3485 [hep-ph].\n\nhttps://indico.particle.mephi.ru/event/35/contr ibutions/2163/ LOCATION:Zoom HEP Theory URL:https://indico.particle.mephi.ru/event/35/contributions/2163/ END:VEVENT END:VCALENDAR