BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Revisiting the Polyakov loop Nambu-Jona-Lasonio model at finite de nsity of baryon charge DTSTART;VALUE=DATE-TIME:20201221T101000Z DTEND;VALUE=DATE-TIME:20201221T103000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-177@indico.bitp.kiev.ua DESCRIPTION:Speakers: Oleksii Ivanytskyi (Bogolyubov Institute for Theoret ical Physics)\nWe revisit the Polyakov Loop coupled Nambu-Jona-Lasinio mod el that maintains the Polyakov loop dynamics at zero temperature\, which i s the most interesting for astrophysical applications. For this purpose we re-examine potential for the deconfinement order parameter at finite bary onic densities. Secondly\, and the most important\, we explicitly demonstr ate that naive modification of this potential at any temperature is formal ly equivalent to assigning a baryonic charge to gluons. We develop a gener al formulation of the present model which is free of the discussed defect and is normalized to asymptotic of the QCD equation of state given by $\\m athcal{O}(\\alpha_s^2)$ perturbative results. We also demonstrate that inc orporation of the Polyakov loop dynamics to the present model sizably stif fens the quark matter equation of state supporting an existence of heavy c ompact stars with quark cores.\n\nhttps://indico.bitp.kiev.ua/event/7/cont ributions/177/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/177/ END:VEVENT BEGIN:VEVENT SUMMARY:Conformational solitons in DNA macromolecule DTSTART;VALUE=DATE-TIME:20201223T100000Z DTEND;VALUE=DATE-TIME:20201223T104500Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-216@indico.bitp.kiev.ua DESCRIPTION:Speakers: Sergej Volkov (Bogolyubov Institute for Theoretical Physic)\nAccuracy of genetic information implementation in living cells is largely due to the peculiarities of the structure and variability of DNA double helix. The regulation of genetic activity\, stability and security of genetic texts\, reading and translation of genetic information\, all of these important biological processes take place because of the unique pro perties of the DNA double helix\, which distinguish them from other cellul ar molecules. One of the key properties of DNA molecule is the polymorphis m of its double helix\, through which this molecule has the ability to cha nge the structure on some definite sites under the influence of external f actors or depending on the nucleotide sequence. Arising in this case local ized deformations can have a sufficiently large amplitude of structural el ement deviations from their equilibrium positions in the double helix and are the conformational solitons by their nature. Such localized deformatio ns cannot be understood within the framework of the elastic rod model\, wh ich is suitable for studying DNA mechanics in a harmonic approximation. On the other hand\, the all-atomic modelling cannot frequently explain the m echanism of DNA double helix deformations due to the complex character of macromolecule structure changes and many degrees of freedom of the double helix. \nThe report presents an approach for the consideration of conforma tion-dependent deformations in DNA macromolecule. The transformation of th e DNA structure is considered in the frame of the two-component model. One model component (external) describes the macromolecule deformation as in the model of the elastic rod\, another component (internal) - the conforma tion changes of the macromolecule monomer units. Both components are consi dered as interconnected on the paths of certain conformational transformat ion. The approach provides the possibility to predict the sizes and energi es of local deformations of the double helix and explained the appearance of solitary excitations in the DNA chain at the location of some definite nucleotide sequences. \nThe results obtained make it possible to uniforml y interpret the long-range soliton effects in the DNA chain\, the deformab ility of specific DNA sequences\, as well as the threshold nature of the e ffects of DNA unzipping and overstretching. The presented results can also be useful for a deeper understanding of the mechanisms of DNA functioning in the cell\, and for the development of modern technologies in the field s of molecular medicine\, DNA engineering\, smart materials and nanodevice s.\n\nThe lecture is dedicated to the memory of A.S. Davydov - an outstand ing scientist\, academician of the National Academy of Sciences of Ukraine \, Hero of Socialist Labor\, and director of the Institute of Theoretical Physics of the National Academy of Sciences of Ukraine (1973-1988).\n\nhtt ps://indico.bitp.kiev.ua/event/7/contributions/216/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/216/ END:VEVENT BEGIN:VEVENT SUMMARY:Dynamics of K$^+$ counterions around DNA double helix in the exter nal electric field: a molecular dynamics study DTSTART;VALUE=DATE-TIME:20201223T135000Z DTEND;VALUE=DATE-TIME:20201223T141000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-182@indico.bitp.kiev.ua DESCRIPTION:Speakers: Oleksii Zdorevskyi (Bogolyubov Institute for Theoret ical Physics )\nThe structure of DNA double helix is stabilized by metal c ounterions condensed to a diffuse layer around the macromolecule. The dyna mics of counterions in real conditions is governed by the electric fields from DNA and other biological macromolecules. In the present work\, the mo lecular dynamics study was performed for the system of DNA double helix wi th neutralizing K$^+$ counterions and for the system of KCl salt solution in an external electric field of different strength (up to 32 mV/ Å). The analysis of ionic conductivities of these systems has shown that the coun terions around the DNA double helix are slowed down compared with the KCl salt solution. The calculated values of ion mobility are within (0.05–0. 4) mS/cm depending on the orientation of the external electric field relat ive to the double helix. Under the electric field parallel to the macromol ecule\, K$^+$ counterions move along the grooves of the double helix stayi ng longer in the places with narrower minor groove. Under the electric fie ld perpendicular to the macromolecule\, the dynamics of counterions is les s affected by DNA atoms\, and starting with the electric field values abou t 30 mV/ Å the double helix undergoes a phase transition from a double-st randed to a single-strand state.\n\nhttps://indico.bitp.kiev.ua/event/7/co ntributions/182/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/182/ END:VEVENT BEGIN:VEVENT SUMMARY:Indirect dark matter search with future X-ray missions DTSTART;VALUE=DATE-TIME:20201222T080000Z DTEND;VALUE=DATE-TIME:20201222T083000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-170@indico.bitp.kiev.ua DESCRIPTION:Speakers: Denys Malyshev (IAAT/Tubingen University)\nDark matt er (DM) remains one of the greatest problems to our understanding of cosmo logy. \n\nIn this talk I will briefly review several SM extensions which n aturally provide dark matter candidates\, including sterile neutrino\, axi on-like particles and dark photons. We will review existing constraints on the parameters of DM candidates and perspectives for indirect DM searches as well as discuss the improvement in the area which can be achieved with the next-generation X-ray missions such as Athena\, eXTP and THESEUS.\n\n https://indico.bitp.kiev.ua/event/7/contributions/170/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/170/ END:VEVENT BEGIN:VEVENT SUMMARY:Equation of State at Finite Baryon Density and External Magnetic F ield from Lattice QCD DTSTART;VALUE=DATE-TIME:20201221T091000Z DTEND;VALUE=DATE-TIME:20201221T093000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-171@indico.bitp.kiev.ua DESCRIPTION:Speakers: Natalia Kolomoyets (JINR)\nThe report is devoted to lattice study of QCD equation of state (EoS) at finite baryon chemical po tential and nonzero external magnetic field. The simulations are performed with rooted dynamical staggered $u$\, $d$\, and $s$ quarks at physical qu ark masses. In view of the sign problem\, the study is carried out at imag inary chemical potential. The results are analytically continued to real chemical potential domain. We present our preliminary results for pressure computed for various values of temperature and magnetic field.\n\nhttps:/ /indico.bitp.kiev.ua/event/7/contributions/171/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/171/ END:VEVENT BEGIN:VEVENT SUMMARY:Femtoscopic analysis of relativistic heavy-ion collisions in the h ydrokinetic approach DTSTART;VALUE=DATE-TIME:20201221T103000Z DTEND;VALUE=DATE-TIME:20201221T105000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-167@indico.bitp.kiev.ua DESCRIPTION:Speakers: Musfer Adzhymambetov (Bogolyubov Institute for Theor etical Physics)\nThe theoretical description of the femtoscopy scales in u ltrarelativistic heavy-ion collisions at different energies and for differ ent colliding ion pairs (Au + Au collisions at the top RHIC energy $\\sqrt {s_{NN}}=200$ GeV\, Pb + Pb collisions at the LHC energies $\\sqrt{s_{NN}} =2.76$ and $\\sqrt{s_{NN}}=5.02$ TeV\, the LHC Xe + Xe collisions at $\\sq rt{s_{NN}}=5.44$ TeV) is provided within the integrated HydroKinetic model (iHKM). The comparison of the model simulation results\, obtained for the considered collision types at the similar values of the mean charged part icle multiplicity ⟨$dNch/dη$⟩ shows that the magnitudes of the corres ponding interferometry radii depend not only on ⟨$dNch/dη$⟩ but also on the geometric sizes of the colliding nuclei.\n\nhttps://indico.bitp.kie v.ua/event/7/contributions/167/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/167/ END:VEVENT BEGIN:VEVENT SUMMARY:Coulomb and vibration effects in spin-polarized current through a single-molecule transistor DTSTART;VALUE=DATE-TIME:20201221T131500Z DTEND;VALUE=DATE-TIME:20201221T133500Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-186@indico.bitp.kiev.ua DESCRIPTION:Speakers: Anastasiia Shkop (B. Verkin Institute for Low Temper ature Physics and Engineering of the NAS of Ukraine)\nIn recent years nano scale transistors gain more scientific interest. The single-molecule trans istor\, where vibrating molecule is placed between two massive electrodes\ , appears to be a challenging device for further fundamental study and app lication in electronics. In this device along with the possibility of elas tic tunneling the electrons can tunnel inelastically\, emitting or absorbi ng vibrons. New transport phenomena also occur while the current of spin-p olarized carriers through molecular transistor is controlled by an externa l magnetic field\, providing an application in spintronics.\n\nThe current through spintronic molecular transistor in an external magnetic field is studied. We consider a molecule placed between electrodes\, which are full y spin-polarized in opposite directions. The electron-vibron interaction a nd the Coulomb correlations in the system are taken into account. It is kn own that the dependence of the current on bias voltage in molecular transi stors at low temperatures have form of step-like function (see e.g. [1]). Current jumps (Franck-Condon steps) occur\, when new inelastic tunnel chan nels open. \n\nFig.1: The dependence of current on bias voltage $I(V)/I_0$ for spintronic molecular transistor at low temperatures for different val ues of Coulomb interaction (solid thin curve corresponds to negligibly sma ll Coulomb interaction). $I_0=e\\Gamma/(2\\hbar)$\, where $\\Gamma$ is the tunneling level width. The bias voltage in energy units is normalized to molecule’s vibration quantum.\n\nThe average current has been found usin g the density matrix method in perturbation theory over tunnel coupling. I t has been obtained that the current dependences in our model have doubled number of Franck-Condon steps (Fig. 1) compared to an “ordinary” mole cular transistor. The doubling is due to the appearance of second elastic channel in the system with Zeeman splitting. It has been revealed that for strong Coulomb interaction the heights of Frank-Condon steps are suppress ed (solid thick\, dotted and dashed curves\, Fig. 1) and the regions witho ut steps on the current-voltage characteristics appear (dotted and dashed curves\, Fig. 1). The effects are caused by interplay of Franck-Condon and Coulomb blockade lifting by bias voltage. It has been also shown that the lifting of the Coulomb blockade in the Zeeman split system procceds in st ages. It has been obtained that the temperature dependence of a conductanc e of spintronic molecular transistor for strong electron-vibron interactio n is anomalously nonmonotonic in the region of intermediate temperatures i n a wide range of external magnetic fields and at arbitrary Coulomb energy . \nThe results lead to a better understanding of the transfer of the curr ent of interacting carriers in complex systems\, allow one to interpret th e data of tunnel experiments\, provide background for engineering of nanoe lectronic devices controlled by an external magnetic field.\n\nhttps://ind ico.bitp.kiev.ua/event/7/contributions/186/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/186/ END:VEVENT BEGIN:VEVENT SUMMARY:Annihilating Dark Matter Search with 12 Years of Fermi LAT Data in Nearby Galaxy Clusters DTSTART;VALUE=DATE-TIME:20201222T083000Z DTEND;VALUE=DATE-TIME:20201222T085000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-168@indico.bitp.kiev.ua DESCRIPTION:Speakers: Charles Thorpe-Morgan (Institut für Astronomie und Astrophysik - University of Tübingen)\nGalaxy clusters are the largest vi rialised objects in the Universe\, and as such\, have a high dark matter ( DM) concentration. This abundance of dark matter makes them promising targ ets for indirect DM searches. Here we report the details of a search\, uti lising almost 12 years of Fermi/LAT data\, for gamma ray signatures from t he pair annihilation of WIMP dark matter in the GeV energy band. From this \, we present the constraints on the annihilation cross section for the bb \, W+W- and γγ channels\,derived from the non-detection of a characteris tic signal from five nearby high galactic latitude galaxy clusters (Centau rus\, Coma\, Virgo\, Perseus and Fornax). We discuss the potential of a bo ost to the signal due the presence of substructures in the DM halos of sel ected objects\, as well as the impact of uncertainties in DM profiles on t he presented results. We assert that the obtained limits are\, within a sm all factor\, comparable to the best available limits of those based on Fer mi/LAT observations of dwarf spheroidal galaxies.\n\nhttps://indico.bitp.k iev.ua/event/7/contributions/168/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/168/ END:VEVENT BEGIN:VEVENT SUMMARY:Dark Matter Polarization Operator in the Generalized Yukawa Model DTSTART;VALUE=DATE-TIME:20201222T131000Z DTEND;VALUE=DATE-TIME:20201222T133000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-179@indico.bitp.kiev.ua DESCRIPTION:Speakers: Mykyta Dmytriiev ()\nThe dark matter particle candid ates are searched on various modern colliders\, but nothing has been found \, yet. The possible reason for this is considered in this work. In the on -resonance search method of the new particle\, the latter is identified wi th the resonant peak in the cross-section of some scattering process. The resonance position coincides with the mass of the particle\, and its width is defined as peak width on the half of its height. It is assumed in the experimental data treatment that the new resonance is narrow\, namely its width is up to $3\\%$ of its mass. If it is wider\, such state could be mi ssed in the data as a noise. We consider different scenarios in which dark matter candidate acquires bigger width\, and identify the new particle pa rameters at which it happens.\n \nWe conduct our research in the framework of the generalized Yukawa model\, where dark matter is presented as a sca lar field $\\chi$ and a Dirac fermionic field $\\Psi$. The model also cont ains the sector of visible matter particles\, which consists of scalar fie ld $\\phi$ and Dirac fermionic fields $\\psi_1$ and $\\psi_2$. The lagrang ian of the model reads:\n\n$\n \\mathcal{L} = \\frac{1}{2}\\left[\\lef t(\\partial_{\\mu}\\phi\\right)^2 - \\mu^2\\phi^2 + \\left(\\partial_{\\mu }\\chi\\right)^2 - \\Lambda^2\\chi^2\\right] - \\lambda\\phi^4 - \\rho\\ph i^2\\chi^2 - \\xi\\chi^4 + $\n$\n + \\sum\\limits_{a=1\;2}\\bar{\\psi} _a\\left(i\\gamma^{\\mu}\\partial_{\\mu} - m_a - g_{\\phi}\\phi - g_{\\chi }\\chi\\right)\\psi_a + \\bar{\\Psi}\\left(i\\gamma^{\\mu}\\partial_{\\mu} - M - G_{\\chi}\\chi\\right)\\Psi.\n$\n\nWidth of the $\\chi$ particle is defined generally by the imaginary part of its polarization operator $\\P i_{\\chi\\chi}(p^2)$ taken at the point $p^2 = \\Lambda^2$. Here $p^2$ is the squared momentum transferred through the virtual bosonic state. $\\Pi_ {\\chi\\chi}(p^2)$ is found analytically. Hence\, the width $\\rho$ of the $\\chi$ resonance\, as a fraction of mass $\\Lambda$\, reads:\n\n$$\n \\rho = \\frac{\\Im\\Pi_{\\chi\\chi}(\\Lambda^2)}{\\Lambda^2} = \\frac{g_ {\\chi}^2}{8\\pi}\\left[\\left(1 - \\frac{4m_1^2}{\\Lambda^2}\\right)^{\\f rac{3}{2}} + \\left(1 - \\frac{4m_2^2}{\\Lambda^2}\\right)^{\\frac{3}{2}}\ \right] + \\frac{G_{\\chi}^2}{\\Lambda^2}\\left(1 - \\frac{4M^2}{\\Lambda^ 2}\\right)^{\\frac{3}{2}}.\n$$\nThe lagrangian also introduces the mixing of scalar fields\, which occurs on the one-loop level. That is\, two-point Green function $\\left$ becomes non-zero due to the loop correction from the $\\psi_1$ and $\\psi_2$\, which connects $\\phi$ and $\\chi$ lines on the corresponding diagram. The magnitude of such mixing is defined by the corresponding mixing angle $\\theta_{mix}$. We define this angle from the diagonalization of the bosonic mass matrix\, which is given by the effecti ve potential of the scalar fields. Hence\, $\\theta_{mix}$ reads:\n\n$$\n\ \tan{2\\theta_{mix}} = 2g_{\\phi}g_{\\chi}F\\left[\\frac{4\\pi^2}{3}\\left (\\Lambda^2 - \\mu^2\\right) + \\left(g_{\\phi}^2 - g_{\\chi}^2\\right)F - G_{\\chi}^2M^2\\ln\\frac{M^2}{\\kappa^2}\\right]^{-1}\, \n$$\n$$\nF = m_1 ^2\\ln\\frac{m_1^2}{\\kappa^2} + m_2^2\\ln\\frac{m_2^2}{\\kappa^2}\,\n$$\n \nwhere $\\kappa$ is an arbitrary renormalization parameter.\n \nFrom the explicit analytical expression\, we find areas of the model parameters spa ce where $\\rho\\cdot 100\\% > 3\\%$. We find that the limit of $3\\%$ can be exceeded in many cases. In the framework of our model\, the conditions for that are the following. There should be $\\Lambda > \\mu$\, so DM par ticle is heavier than the visible one. Additionally\, interactions in the visible sector should be weaker than that of between the dark and visible particle or between the particles in the dark sector only. That is\, if ei ther $g_{\\chi} \\gg g_{\\phi}$ or $G_{\\chi} \\gg g_{\\phi}$. Finally\, t here exists an upper bound for the mixing angle -- in our model\, it shoul d be $|\\theta_{mix}|\\leq 10^{-5}$. We find that until mixing between vis ible and dark bosons is small and two resonances are located far enough on e from another\, the parameters of visible particle resonance are independ ent of the characteristics of the dark sector. In this case dark resonance is both wide and does not interfere with the resonance of visible $\\phi$ . The presence of the upper limit on $\\theta_{mix}$ is qualitatively impo rtant.\n \nThe self-interaction of the bosonic particles does not affect t heir widths\, being canceled in the renormalization procedure.\n \nThe con sidered Yukawa model gave a possibility for analyzing the role of the mass es and couplings of particles. Other aspects of the problem such as group symmetry of the extended model and\, hence\, the content of the states rem ain behind it. However\, we have obtained the set of conditions which have to be taken into account when searches for the DM particles are carried o ut. In general\, to avoid the problem of wide resonance states we have to apply additionally non-resonant methods to detect these new states of matt er.\n\nhttps://indico.bitp.kiev.ua/event/7/contributions/179/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/179/ END:VEVENT BEGIN:VEVENT SUMMARY:Bose-Einstein condensation phenomenology in systems with repulsive interactions DTSTART;VALUE=DATE-TIME:20201221T093000Z DTEND;VALUE=DATE-TIME:20201221T095000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-173@indico.bitp.kiev.ua DESCRIPTION:Speakers: Oleh Savchuk (Frankfurt Institute For Advanced Studi es)\nThe role of repulsive interactions in statistical systems of Bose par ticles is investigated. Three different phenomenological frameworks are co nsidered: a mean field model\, an excluded volume model\, and a model with a medium dependent effective mass. All three models are tuned to yield si milar equations of state\, with only minor deviations from the ideal Bose gas at small chemical potentials. Our analysis indicates\, however\, that these models lead to qualitatively different results for the Bose-Einstein condensation phenomenon. We discuss the different aspects of this phenome non\, namely\, an onset of the Bose-Einstein condensation\, particle numbe r fluctuations\, and a behavior of the Bose condensate. The obtained resul ts can be helpful for interpreting the lattice QCD data at small temperatu re and large isospin chemical potential and the data on multiple pion prod uction in high energy nuclear collisions.\n\nhttps://indico.bitp.kiev.ua/e vent/7/contributions/173/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/173/ END:VEVENT BEGIN:VEVENT SUMMARY:Production of HNL in 3-body decays of mesons. Comparison with PYTH IA approach DTSTART;VALUE=DATE-TIME:20201221T105000Z DTEND;VALUE=DATE-TIME:20201221T111000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-176@indico.bitp.kiev.ua DESCRIPTION:Speakers: Yuliia Borysenkova (Taras Shevchenko National Univer sity of Kyiv)\nThe Standard Model (SM) is a particle physics theory that i s consistent up to very high energy scales and verified in numerous exper iments up to $\\sim 14$ TeV. However\, it fails to explain some phenomena such as massiveness of neutrinos\, dark matter\, dark energy\, baryon as ymmetry of the Universe etc. Therefore SM is incomplete and requires an ex tension. \n\nOne possible approach is by adding new particles to the theor y. There are two possible answers to the question "Why do we not observe p articles of new physics in experiments?" The first answer is the following . The new particles are very heavy and can not be produced in modern ac celerators like LHC. To detect them one has to build more powerful and mor e expensive accelerators. There is another possibility. The particles of n ew physics can be light particles that feebly interact with SM particles. \nThe last case is very interesting for the experimental search of the new physics in the intensity frontier experiments just now. There are differe nt choices of new renormalized interaction Lagrangian of particles of new physics with SM particles. It's called portals. \n\nIn this paper\, we co nsider a heavy neutral lepton (HNL) portal. The phenomenology of GeV-scale HNL was considered in details in [1]. We will compare the analytical resu lts for HNL production in 3-body decays of mesons with PYTHIA approximatio n. \n\nThe simplest way of neutrino modification of the SM involves extens ion of the SM by neutrino singlets with right chirality (in the SM all rig ht-handed fermions are singlets)\, which extremely faintly interact with S M particles. Such neutrinos are called sterile neutrinos or heavy neutral leptons. Renormalized and gauge-invariant interaction of new neutrinos w ith the SM particles is similar to the Yukawa interaction of left-handed q uarks doublets with singlets of the right-handed quarks\, namely:\n\n$$\n\ \mathcal L_{int}=-\\left(F_{\\alpha I}\\bar L_\\alpha \\tilde H\nN_I+h.c.\ \right)\,\n$$\n\nwhere $\\alpha=e\,\\mu\,\\tau$\, index $I$ \nis from 1 t o full number of the sterile neutrinos\, $L_{\\alpha}$ –\ndoublet of le ptons of $\\alpha$-generation\, $N_I$ – right-handed sterile neutrino\,\ n$F_{\\alpha\nI}$ – new matrix of dimensionless Yukawa couplings\, ${\\t ilde H}=i\\sigma_2H^\\star$.\n\nTaking the low energy limit and considerin g sterile neutrino as Majorana particles\, we can write full Lagrangian of the modified neutrino sector of the SM\n\n$$\n\\mathcal{L}_{\\nu\,N}=i \\ bar{\\nu_k} \\not\\partial \\nu_k + i \\bar{N_I} \\not\\partial N_I -\n \ \left( F_{\\alpha I}\\bar{\\nu}_{\\alpha} N_I + \\frac{M_{I}}{2} \\bar{N_I }^c N_I + h.c. \\right)\,\n$$\n\nwhere $M_I$ – Majorana mass terms.\nAs a result of the neutrino states mixture\, the active neutrino states beco me superposition of the mass states of the active and the sterile neutrino s.\nIt means that sterile neutrinos interact with SM particles similarly t o active neutrinos:\n\n$$\n\\mathcal{L}_{int} = -\\biggl(\\frac{g}{2\\sqrt 2} W^+_\\mu\\!\\sum_{I\,\\alpha} \\overline{N^c}_I U_{I\\alpha} \\gamma^ \\mu (1-\\gamma_5) \\ell^-_\\alpha + \\frac{g}{4 \\cos\\theta_W}Z_\\mu\\! \\sum_{I\,\\alpha}\\overline{N^c}_I U_{I\\alpha} \\gamma^\\mu (1-\\gamma_ 5) \\nu_\\alpha + h.c.\\biggr)\,\n$$\n\nwhere $U_{I\\alpha}=F_{I\\alpha}/M _I$ is so called mixing angle.\n\nFor intensity frontier experiment it is very important to built sensitivity region. It is a region in space of p arameters of new particle (mass and coupling)\, when particle can be detec ted in the experiment. To build it one has to solve inequality $N_{HNL}^{r eg}>N_0$\, where $N_0$ is minimal expected number of new particle for succ essful of experiment\, $N_{HNL}^{reg}$ is number of HNL that can be detect ed:\n\n$$\nN_{HNL}^{reg}\\simeq N^{produced}_{HNL} P_{geom} P_{decay}.\n$$ \n\nHere $N_{HNL}^{produced}$ is number of\nthe produced \\textit{HNL}-pa rticles\, $P_{geom}$ is a probability of the produced HNL-particles to mov e towards the detector\, $P_{decay}$ is a probability of the\nproduced HNL -particles to decay in the volume of the vacuum tank\nbefore the detectors .\n\nFor approximate calculations of the sensitivity region\, PYTHIA is of ten used. It is a widely used program for the generation of high-energy ph ysics events.\nPYTHIA is good for generation of 2-body mesons' decay\, but for HNL production it is important to take into account 3-body decay too. \nPYTHIA uses predefined matrix element to generate 3-body semileptonic de cays of $B$ and $D$ mesons correspondingly\n\n$$\n \\overline{|M_{fi}| ^2_B} = (p_h\\\,p_\\nu) (p_{h^\\prime} \\\, p_\\ell)\,\\quad \n \\overl ine{|M_{fi}|^2_D} = (p_h\\\,p_\\ell) (p_{h^\\prime} \\\, p_\\nu).\n$$\n\n It does not contain mesons' form-factors and its matrix elements obviousl y\ndiffers from correct matrix elements for HNL production in 3-body meson s' decay.\nThe goal of the project is to estimate the importance of this u ncertainty for construction of sensitivity region to HNL.\n\nWe considere d in details probability density function for the energy of the HNL-parti cles $pdf(E_N)$\, $P_{geom}$ and $P_{decay}$ and make following conclusio ns.\n\n\n\nComputations of 3-body decay of $\\tau$-lepton with HNL produc tion in Pythia coincide with correct computations.\n\nFor description of r eactions of pseudoscalar meson 3-body decay into another pseudoscalar meso n ($B^- \\rightarrow D^0 +\\ell^- + N$ and $D^- \\rightarrow K^0 +\\ell^- + N$) the matrix elements of type $B$ in Pythia is better to use \n\nFor description of reactions of pseudoscalar meson 3-body decay into another vector meson ($B^- \\rightarrow D^\\star(2007)^0 +\\ell^- + N$ and $D^- \\ rightarrow K^\\star(892)+\\ell^- + N$) the matrix elements of type $D$ in Pythia is better to use.\n\nAmong the considered 3-body reactions\, due to a suitable choice of PYTHIA matrix elements (type of $B$ and $D$)\, one c an get the smallest difference with correct matrix element for reaction $B^- \\rightarrow D^0 +e^- + N$ (difference $\\sim 1\\%$)\, while the larg est unremovable difference is for reaction $D^- \\rightarrow K^\\star(89 2) +e^- + N$ (difference $\\sim 5\\%$).\n\n\n\n[1] Kyrylo Bondarenko\, Alexey Boyarsky\, Dmitry Gorbunov\, and Oleg Ruchayskiy. Phenomenolo gy of GeV-scale Heavy Neutral Leptons. *JHEP*\, 11:032\, 2018.\n\nhttps:// indico.bitp.kiev.ua/event/7/contributions/176/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/176/ END:VEVENT BEGIN:VEVENT SUMMARY:Phenomenology of GeV-scale Chern-Simons boson DTSTART;VALUE=DATE-TIME:20201221T111000Z DTEND;VALUE=DATE-TIME:20201221T113000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-175@indico.bitp.kiev.ua DESCRIPTION:Speakers: Mariia Tsarenkova (Taras Shevchenko National Univers ity of Kyiv)\nThe Standard Model (SM) is a particle physics theory that is consistent up to very high energy scales and verified in numerous experi ments up to $\\sim 14$ TeV. However\, it fails to explain some phenomena such as massiveness of neutrinos\, dark matter\, dark energy\, baryon asy mmetry of the Universe etc. Therefore\, SM is incomplete and requires an e xtension. \n\nOne possible approach is by adding new particles to the theo ry. There are two possible answers to the question "Why do we not observe particles of new physics in experiments?" The first answer is the followin g. The new particles are very heavy and can not be produced in modern a ccelerators like LHC. To detect them one has to build more powerful and mo re expensive accelerators. There is another possibility. The particles of new physics can be light particles that feebly interact with SM particles .\nThe last case is very interesting for the experimental search of the ne w physics just now. There are three possible choices of new renormalized i nteraction Lagrangian of particles of new physics with SM particles. It's called portals. There are scalar portal\, heavy neutral leptons portal\, vector portal. There are other portals of high-dimensional operators such as portal of pseudoscalar particles (axion-like particles)\, or Chern-Simo ns like (parity odd) interaction of electroweak gauge bosons with a new ve ctor field [1].\n\n\nIn this paper\, we consider a Chern-Simons (CS) porta l with new neutral vector particle ($X$) boson. \nThis extension has not yet been studied sufficiently. This interaction was proposed in [2]. It origins from non-trivial anomaly cancellations in theory with new heavy fe rmions. It has gauge-invariant form\n$$\n \\mathcal{L}_1=\\frac{C _Y}{\\Lambda_Y^2}\\cdot X_\\mu (\\mathfrak D_\\nu H)^\\dagger H B_{\\lambd a\\rho} \\cdot\\epsilon^{\\mu\\nu\\lambda\\rho}+h.c.\, \\quad \n\ \mathcal{L}_2=\\frac{C_{SU(2)}}{\\Lambda_{SU(2)}^2}\\cdot X_\\mu (\\mathfr ak D_\\nu H)^\\dagger F_{\\lambda\\rho} H\\cdot\\epsilon^{\\mu\\nu\\lambda \\rho}+h.c. \n$$\n\nIn the low energy limit (unitary gauge) the effective renormalized Lagrangian of three particle interaction CS boson with SM pa rticles is\n$$\n \\mathcal{L}_{CS}=c_z \\epsilon^{\\mu\\nu\\lambda\\rho} X_\\mu Z_\\nu \\partial_\\lambda Z_\\rho +c_\\gamma \\epsilon^{\\mu\\nu\\l ambda\\rho} X_\\mu Z_\\nu \\partial_\\lambda A_\\rho+\\left\\{ c_w \\epsil on^{\\mu\\nu\\lambda\\rho} X_\\mu W_\\nu^- \\partial_\\lambda W_\\rho^+ + h.c.\\right\\}.\n$$\n\nFor the experimental search of the new particle\, i t is very important to theoretically consider channels of production and d ecay of the new particle. We consider the case of experiments on Cern SPS accelerator\, where CS particles can not be produced from the decay of rea l $W$\, $Z$ bosons. In this paper\, we consider the production of CS GeV- scale particles in mesons' decay. \n \nTo do it we get effective Lagrangia n of CS interaction with different quarks due to presented here loop diagr am in the form\n$$\n \\mathcal{L}_{CSd}= \\sum_{m\\neq n}\\Theta_{1W} \\left( C^d_{mn}\\\, \\bar{\\Psi}_{d_n}\\\, \\gamma^{\\mu}\\\,\\hat\n P_L \\\, \\Psi_{d_m} X_{\\mu}+h.c.\\right)%-\\sum_n\\Theta_W^1 g^2 C^d_{nn}\\\, \\bar{\\Psi}_{d_n}\\\, \\gamma^{\\mu}\\\,\\hat P_L \\\, \\Psi_{d_n} X_{\\mu}\,\n$$\nwhere $\\Theta_{1W}$ is real part of $c_w$ c oupling and $C^d_{bs}=1.97\\cdot 10^{-4}$\, $C^d_{bd}=4.43\\cdot 10^{-5}$\ , $C^d_{sd}=1.77\\cdot 10^{-6}$.\nAs it turned out the loop with different quarks does not suffer from divergence problem and we have to take into a ccount only interaction with down quarks\, because coefficients of intera ction with up quarks are sufficiently smaller. \nSo\, we will consider CS particle production in meson's decay only due to decay of heavy down quark in the meson. \n\nInitial lightest mesons containing $b$ and $s$ quarks are $B$-mesons and $K^\\pm$\, $K^0_S$\, $K^0_L$ mesons.\n\nPossible reacti on of $B$-meson decay with $X$-particle production is decay into pseudosca lar mesons ($K$ and $\\pi$ mesons)\, scalar mesons ($K^{0\\star}(700)$\, $K^{0\\star}(1430)$)\, vector mesons ($K^\\star(892)$\, $K^\\star(1410)$\, $K^\\star(1680)$)\, pseudovector mesons ($K_1(1270)$\, $K_1(1400)$) and t ensor final meson states ($K_2(1430)$).\n\nFor the initial kaons states\, the only possible 2-body decay is the process $K \\to \\pi +X$.\nThere are 3 types of the kaons: $K^{\\pm}$\, $K^0_L$\, $K^0_S$. Since $K^0_S$ is th e $CP$-even eigenstate\, the decay $K^0_S\\to \\pi S$ is proportional to t he CKM $CP$-violating phase and is strongly suppressed. Further we assume that the corresponding branching ratio vanishes and consider only reaction s $K^\\pm \\to \\pi^\\pm +X$ and $K^0_L \\to \\pi^0 +X$.\n\nThe amplitude of $h$-meson decay into $h'$-meson and $X$-particle has the form\n\n$$\n M_{h\\rightarrow h'X}=\\Theta_{1W} C^d_{mn} \\\, \\langle h'(p'))|\\ bar d_n\\gamma^{\\mu} \\hat P_L d_m|h(p)\\rangle\\\,\n \\epsilon^{\\sta r\\lambda_X}_{\\mu}.\n$$\n\nThis quantity can be obtained with help of fo rmalism summarised in [3].\n\nIn the following\, we plan to complete consi deration of the production of CS particles by examining direct CS producti on in $p-p$ collisions. Also\, we plan to consider possible channels of CS particles' decay. \n\n\nFigure 1. a) loop diagram of quarks interactions with CS particles\; b) diagram of CS production in meson's decay c) decay of $B$- and $K$-mesons with CS production.\n\n[1] Sergey Alekhin et al. A facility to Search for Hidden Particles at the CERN SPS: the SHiP physics case. *Rept. Prog. Phys.*\, 79(12):124201\, 2016.\n[2] Ignatios Antonia dis\, Alexey Boyarsky\, Sam Espahbodi\, Oleg Ruchayskiy\, and Jame s D.Wells. Anomaly driven signatures of new invisible physics at the Lar ge Hadron Collider. *Nucl. Phys.*\, B824:296–313\, 2010.\n[3] Iryna Bo iarska\, Kyrylo Bondarenko\, Alexey Boyarsky\, Volodymyr Gorkavenko\ , Maksym Ovchynnikov\, and Anastasia Sokolenko. Phenomenology of GeV-scal e scalar portal. *JHEP*\, 11:162\, 2019.\n\nhttps://indico.bitp.kiev.ua/ev ent/7/contributions/175/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/175/ END:VEVENT BEGIN:VEVENT SUMMARY:Probing Solar Chromosphere Through Mg II h and k Wings at 280 nm DTSTART;VALUE=DATE-TIME:20201222T095000Z DTEND;VALUE=DATE-TIME:20201222T101000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-174@indico.bitp.kiev.ua DESCRIPTION:Speakers: Andrii V. Sukhorukov (Main Astronomical Observatory\ , NAS of Ukraine\; Instituto de Astrofisica de Canarias\, Tenerife\, Spain )\nThe Chromospheric Layer Spectro-Polarimeter (CLASP2) was launched on Ap ril 11\, 2019\, from White Sands Missile Range on a sounding rocket and re ached an altitude of 274 km above the sea level in the thermosphere. For f ive minutes in operation\, it observed three different targets on the Sun: a quiet disc center\, an active plage\, and a quiet limb. One-dimensional slit spectra were taken in all four Stokes parameters in the vicinity of the resonance doublet of Mg II\, the so-called h and k lines at 280 nm in the ultraviolet. A weak signal\, although at the noise level\, of linear p olarization due to spatial symmetry breaking on atmospheric granulation wa s detected at the disc center target. The plage target showed strong sign atures of the longitudinal Zeeman effect\, as expected. The limb target r evealed Q/I profile shapes due to the J-state interference in a two-term a tom. This was the first observational confirmation of a theoretical effect predicted by Belluzzi and Trujillo Bueno (2012).\nIn order to interpret t hese observations\, we developed two numerical modules for the radiative t ransfer code PORTA (Stepan and Trujillo Bueno\, 2013). One module solves t he polarized transfer equations neglecting effects due to magnetic fields\ , while the other includes the Faraday rotation via selected magneto-optic al terms. Both modules account for the J-state interference as well as the partial redistribution of photons\, scattered in the resonance doublet. A s the general treatment of resonance scattering is too expensive\, we appr oximated it by applying the atomic coherent scattering function in the obs erver's frame. This approximation kept the essential magnetic sensitivity in the wings and dramatically reduced computational costs. With both modul es\, we numerically solved the transfer problem in the wings of the Mg II doublet for a two-term model atom and using a model chromosphere from the so-called ``enhanced network simulations'' produced by the radiation-MHD c ode Bifrost (Carlsson et al. 2016). We generated both synthetic images as well as slit spectra in all four Stokes parameters for different positions on the solar disk\, which we compared against observations.\n\nIn this ta lk\, I'll describe the observational experiment\, the theoretical method\, the complexity and computational demands of resonance scattering and how it can be approximated\, which quantum effects define the observed shapes of the Stokes profiles\, how sensitive to magnetic fields are the line win gs\, and why there are discrepancies between observed and calculated spect ra.\n\nhttps://indico.bitp.kiev.ua/event/7/contributions/174/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/174/ END:VEVENT BEGIN:VEVENT SUMMARY:S-Matrix unitarity and Pomeron shadowing corrections DTSTART;VALUE=DATE-TIME:20201222T133000Z DTEND;VALUE=DATE-TIME:20201222T135000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-178@indico.bitp.kiev.ua DESCRIPTION:Speakers: Georgy Tersimonov (Bogolyubov Institute for Theoreti cal Physics)\nRegge theory is the only valid framework to describe soft sc attering processes where the perturbative QCD is not applicable. In Regge theory\, the particle diffraction is treated as an exchange of some 'objec t' called Pomeron (which in some way generalizes a particle — in particu lar\, it is described by variable complex angular momentum which generaliz es a spin). That approach was found surprisingly useful to phenomenologica lly calculating cross sections.\nIn 1960s\, it was shown that multi-Pomero n shower production reactions $pp \\rightarrow p + X_1 + X_2 + ... + p$\, where showers $(X_i)$ are separated by large rapidity gaps\, are breaking the S-matrix unitarity because corresponding cross-sections $\\sigma_{tot} $ grow with the rapidity ($\\xi$) faster than allowed by unitarity (the u pper bound is $\\sigma_{tot} \\leq \\xi^2$). This issue is known as Finkel stein-Kajantie problem. In 1974\, a possible solution was proposed [1] in multi-channel Eikonal model. It considered the gap survival probability $S ^2$ — the probability to observe the pure process where the gap is not p opulated by secondaries produced in the additional inelastic interaction. In the impact parameter representation the probability is given by $S^{2}( b) = |e^{-\\Omega(b)}|$\, where $b$ is the impact parameter and $\\Omega$ is the proton opacity. In the black disc limit $Re(\\Omega) \\rightarrow \ \infty$\, so $S^2(b) \\rightarrow 0$. So the additional rescatterings sho uld close the rapidity gaps. The work [2] shows that decreasing of the sur vival probability should overcompensate the original cross-sesction growth so\, as a result\, the cross-sections should also vanish with energy: $\\ frac{d\\sigma}{d\\xi_1} \\sim e^{-{\\Delta}\\xi_1} \\rightarrow 0$\, where $\\xi_1$ is the shower width on the rapidity scale. If the result is corr ect then the unitarity is restored. Over the past decades\, it has been co nsidered a cure for the FK problem [3].\nThe work [4] had discovered that such an approach still fails to unitarize the Pomeron contribution to the single diffraction dissociation amplitude due to an error in the calculati ons. The suspicion had arised: is the cure really effective in terms of al l the processes it is purposed for? Recent TOTEM soft scattering data rene wed the interest to these questions.\nIn the work [5] we investigate the s urvival probability method for all the diffractive processes. The main pro cesses are next. The first is single diffraction dissociation where one of the two incoming protons transforms into a shower: $pp \\rightarrow X + p$. The second is double diffraction dissocastion where both protons trans forms: $pp \\rightarrow X_1 + X_2$. The third is central production: $pp \\rightarrow p + X + p$. Integrated cross-sections of all these processes behave similar to each other\, so only the simplest\, the single dissocia tion\, will be considered in this talk. Its cross-section contains a mult iplier $e^{\\Delta(\\xi_1 + 2\\xi_2 - a\\xi)}$\, where $a \\rightarrow 2\\ frac{\\xi}{\\xi + \\xi_1}$ as $\\xi \\rightarrow \\infty.$ Here $\\xi_2$ i s the rapidity gap between the produced shower and the initial proton\; $\ \xi_1 + \\xi_2 = \\xi$ — the overall rapidity difference between interac ting protons. While investigating the high energy asymptotics ($\\xi \\rig htarrow \\infty$)\, the authors of [2] considered $a$ as $2$ and $e^{\\Del ta(\\xi_1 + 2\\xi_2 - a\\xi)}$ simply became $e^{-\\Delta{\\xi_1}}$. Howev er\, if the calculations are done in an explicit way\, one can see that $a = 2(1 -\\frac{\\xi_1}{\\xi} + O(\\frac{\\xi^2_1}{\\xi^2}))$ and so $e^{\\ Delta(\\xi_1 + 2\\xi_2 - a\\xi)} = e^{\\Delta(\\xi_1 + 2\\xi_2 - 2\\xi (1 -\\frac{\\xi_1}{\\xi}))}$ = $e^{+\\Delta{\\xi_1}}$\, thus the fast cross- section growth is in fact maintained.\nThereby the existing survival proba bility methods are unable to keep the cross-section growth within the unit arity bound. We develop a different approach based on the Pomeron and trip le-Pomeron vertex renormalization via Schwinger-Dyson equations. We take t he Pomeron in it's maximal form providing the maximal strong interactions strength allowed by unitarity. The triple-Pomeron vertex is chosen to cont ain zeroes at some transferred momenta and complex angular momenta. The pa rameters of developing model can be chosen in such a way that the unitarit y bounds are not violated.\n\n[1] J. L. Cardy. General Features of the Reg geon Calculus with $\\alpha > 1$. *Nucl. Phys. B*\, 75 (1974)\n[2] E. Gots man\, E.M. Levin\, U. Maor. Diffractive Dissociation and Eikonalization in High Energy $pp$ and $p\\bar{p}$ Collisions\, *Phys. Rev. D*\, 49 (1994)\ n[3] V.A. Khoze\, A.D. Martin\, M.G. Ryskin. Black disc\, maximal Odderon and unitarity. *Phys.Lett. B*\, 780 (2018)\n[4] E. Martynov\, B. Strumins ky. Unitarized model of hadronic diffractive dissociation. *Phys.Rev. D*\, 53 (1996)\n[5] E. Martynov\, G. Tersimonov. Multigap diffraction cr oss sections: Problems in eikonal methods for the Pomeron unitarization. * Phys. Rev. D*\, 101 (2020)\n\nhttps://indico.bitp.kiev.ua/event/7/contribu tions/178/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/178/ END:VEVENT BEGIN:VEVENT SUMMARY:Revisiting constraints on warm dark matter from the UV luminosity functions DTSTART;VALUE=DATE-TIME:20201222T091000Z DTEND;VALUE=DATE-TIME:20201222T093000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-185@indico.bitp.kiev.ua DESCRIPTION:Speakers: Anton Rudakovskyi (Bogolyubov Institute for Theoreti cal Physics)\nThe ultra-violet luminosity functions (UV LFs) of the galaxi es allow constraining the dark matter particle properties. In the warm dar k matter scenario\, the formation of low-mass galaxies is suppressed\, whi ch may impact the UV LFs.\n\nWe have performed the Bayesian inference on w arm and cold dark matter scenarios via UV LFs at z=6\, 7\, 8. We have fou nd that there is no significant preference for the CDM over WDM by compari ng the Bayesian evidences. Knowing the bayesian evidences allows us to bui ld the combined bounds on the model parameters via different datasets. We have derived the robust combined bound on the warm dark matter particle ma ss $m_\\text{x}\\geq2.1$ keV with 95% confidence level.\n\nhttps://indico. bitp.kiev.ua/event/7/contributions/185/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/185/ END:VEVENT BEGIN:VEVENT SUMMARY:Radio to X-ray multiband sample for automated AGN search DTSTART;VALUE=DATE-TIME:20201222T101000Z DTEND;VALUE=DATE-TIME:20201222T103000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-181@indico.bitp.kiev.ua DESCRIPTION:Speakers: Kyrylo Soroka (Institute of Astronomy\, V.N. Karazin Kharkiv National University\,)\nWe present the sample of 18 846 spectrosc opically confirmed AGNs found throughout radio to X-ray spectral bands. Th e sample consists of 10 344 AGNs selected among SDSS radio galaxies (Best\ , P. N.\; Heckman\, T. M.\, 2012 )\, 5 536 galaxies with z \n\nhttps://ind ico.bitp.kiev.ua/event/7/contributions/181/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/181/ END:VEVENT BEGIN:VEVENT SUMMARY:The equation of state of hot dense qcd- matter\, gravitational wav es and collective flows DTSTART;VALUE=DATE-TIME:20201221T080500Z DTEND;VALUE=DATE-TIME:20201221T085000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-212@indico.bitp.kiev.ua DESCRIPTION:Speakers: Horst Stöcker (FIAS Goethe Universitaet Frankfurt G SI)\nhttps://indico.bitp.kiev.ua/event/7/contributions/212/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/212/ END:VEVENT BEGIN:VEVENT SUMMARY:Size Characteristics for the Hyperbranched Polymers DTSTART;VALUE=DATE-TIME:20201223T094000Z DTEND;VALUE=DATE-TIME:20201223T100000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-187@indico.bitp.kiev.ua DESCRIPTION:Speakers: Khristine Haydukivska (Institute for Condensed Matte r Physics NAS Ukraine)\nIn the present work we calculated size characteris tics of periodic hyperbranched polymers in dilute solution in the vicinity of the $\\theta$ point using the continuous chain model. This model in it s Gaussian approximation allows to receive exact solutions. Both the gyrat ion radius and the hydrodynamic radius were calculated for the bottle-brus h polymer and a tree-like one. We considered the size ratios $\\rho=\\frac {\\sqrt{\\langle R_g^2\\rangle}}{\\langle R_h\\rangle}$ and $g = \\frac{\\ langle R_{g}^2\\rangle}{\\langle R_{g\,chain}^2\\rangle}$\, that allows to describe the characteristic sizes of this topologies. This types of ratio s allow to shed some light on visco-elastic properties of polymer solution s.\n\nhttps://indico.bitp.kiev.ua/event/7/contributions/187/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/187/ END:VEVENT BEGIN:VEVENT SUMMARY:Flat bands in quasi-one-dimensional Josephson junction arrays DTSTART;VALUE=DATE-TIME:20201221T152000Z DTEND;VALUE=DATE-TIME:20201221T154000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-189@indico.bitp.kiev.ua DESCRIPTION:Speakers: Daryna Bukatova (Kyiv Academic University)\nWe study quasi-one-dimensional arrays of inductively coupled Josephson junctions w ith only self-inductance of a cell taken into account. A 2-row anisotropic Josephson junction ladder (JJL) has a flat band in the linear electromagn etic wave spectrum [1]. We derive the equations of motion for a 3-row anis otropic JJL and generalise them for a ladder with an arbitrary number of r ows $ \\kappa \\geq 3 $. In the case of weak damping we obtain the spectru m of linear electromagnetic waves in these arrays. A $ \\kappa $-row JJL h as 3 bands in the spectrum\, two of them are dispersive: the upper band co nsists of $ (\\kappa-1) $ branches\, the lower one of 2 branches\, the ban d in the middle of the spectrum is dispersionless (flat) and is $ (\\kappa - 2) $-fold degenerate. At zero external dc bias current the two lower br anches become flat\, resulting in $ \\kappa $-fold degeneracy of the flat band.\n\n\n*The Authors acknowledge the support by the National Research Foundation of Ukraine grant ”Topological phases of matter and excitation s in Dirac materials\, Josephson junctions and magnets” (No. 2020.02.005 1).*\n\n\n \n\n 1. A. E. Miroshnichenko\, S. Flach\, M.V. Fistul\, Y. Zolo taryuk\, J. B. Page. Breathers in Josephson junction ladders: Resonances a nd electromagnetic wave spectroscopy. $-$ PHYSICAL REVIEW E\, VOLUME 64\, 066601. $-$ 2001.\n\nhttps://indico.bitp.kiev.ua/event/7/contributions/189 / LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/189/ END:VEVENT BEGIN:VEVENT SUMMARY:Effective free-fermionic form factors on a lattice and XY quantum chain DTSTART;VALUE=DATE-TIME:20201222T141000Z DTEND;VALUE=DATE-TIME:20201222T143000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-193@indico.bitp.kiev.ua DESCRIPTION:Speakers: Yurii Zhuravlov (Bogolyubov Institute for Theoretica l Physics of the National Academy of Sciences of Ukraine)\nWe introduce th e effective form factors for one-dimensional lattice fermions with arbitra ry phase shifts. We study tau functions defined as series of these form fa ctors. On the one hand we perform the exact summation and present tau func tions as Fredholm determinants in the thermodynamic limit. On the other ha nd simple expressions of form factors allow us to present the correspondin g series as integrals of elementary functions. Using this approach we re-d erive the asymptotics of static correlation functions of the XY quantum ch ain at finite temperature.\n\nhttps://indico.bitp.kiev.ua/event/7/contribu tions/193/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/193/ END:VEVENT BEGIN:VEVENT SUMMARY:Connecting fluctuation measurements in heavy ion collisions and gr and canonical susceptibilities: global conservation effects DTSTART;VALUE=DATE-TIME:20201221T085000Z DTEND;VALUE=DATE-TIME:20201221T091000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-172@indico.bitp.kiev.ua DESCRIPTION:Speakers: Roman Poberezhnyuk (Bogolyubov Institute for Theoret ical Physics of the National Academy of Sciences of Ukraine)\nWe present t he relation between cumulants of a conserved charge measured in a subvolum e of a thermal system and the corresponding grand-canonical susceptibiliti es\, taking into account exact global conservation of all QCD charges. The derivation is presented for an arbitrary equation of state\, with the ass umption that the subvolume is sufficiently large to be close to the thermo dynamic limit. Our framework – the subensemble acceptance method (SAM) – quantifies the effect of global conservation laws and is an important step toward a direct comparison between cumulants of conserved charges mea sured in central heavy ion collisions and theoretical calculations of gran d-canonical susceptibilities\, such as lattice QCD. We show that the globa l conservation effects cancel out in any ratio of two second order cumulan ts\, in any ratio of two third order cumulants\, as well as in a ratio of strongly intensive measures Σ and ∆ involving any two conserved charges \, making all these quantities particularly suitable for theory-to-experim ent comparisons in heavy-ion collisions. We also show that the same cancel lation occurs in correlators of a conserved charge\, like the electric cha rge\, with any non-conserved quantity such as net proton or net kaon numbe r. The main results of the SAM are illustrated in the framework of the had ron resonance gas model. We also elucidate how net-proton and net-Λ fluct uations are affected by conservation of electric charge and strangeness in addition to baryon number.\n\nhttps://indico.bitp.kiev.ua/event/7/contrib utions/172/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/172/ END:VEVENT BEGIN:VEVENT SUMMARY:Influence of Mismatch Strain on Electrocaloric Properties of Core- Shell Ferroelectric Nanoparticles DTSTART;VALUE=DATE-TIME:20201221T135500Z DTEND;VALUE=DATE-TIME:20201221T141500Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-191@indico.bitp.kiev.ua DESCRIPTION:Speakers: Hanna Shevliakova (Igor Sikorsky KPI)\nFerroelectric s are among the most interesting objects for fundamental and applied studi es of spontaneous polarization dynamics. Special efforts are intended to a nswer the question on how complex topological states such as flux-closure domains\, polarization vortices\, or skyrmions\, which sometimes exist in nanosized ferroelectrics\, can be controlled by elastic forces and/or elec tric fields.\nSeveral authors [1-6] have studied numerically the electroca loric effect (ECE) in ferroelectric nanoparticles using a phase field meth od combined with the Landau-Ginzburg-Devonshire (LGD) approach. These stud ies demonstrate the possibility to reveal a giant ECE in various ferroelec tric nanoparticles\, where the conditions for observing the effect are alm ost always determined in an empirical way\, except for the case of single- domain nanoparticles [7]. Within the framework of the approach we explored the impact of the mismatch strain on ECE of core-shell ferroelectric nano particles with complex domain structure. We performed calculations for a m ultiaxial ferroelectric core covered with a paraelectric shell (see Fig. 1 a)\, with or without mismatch strains. The latter are induced by the diffe rence of the core and shell lattice constants. We studied the influence of the core radius on the electrocaloric cooling temperature and coercive fi eld (see Fig. 1b). We revealed the significant asymmetry of the ferroelect ric properties (transition temperature\, polarization magnitude\, coercive field) and ECE with respect to the sign of the mismatch strain. This resu lt is in a qualitative agreement with experimental results of Barnakov et al. [8]\, who studied the ferroelectric properties of BaTiO3 nanocubes coa ted with metal carboxylates in two forms – one was crystalline and provi ded a lattice mismatch\, and the other was non-crystalline without mismatc h conditions. The revealed polar effects differed by many orders of magnit ude for these two coatings. The analytical results obtained in this study can be used for the optimization of core-shell ferroelectric nanoparticle sizes for advanced applications in nanoelectronics and nano-coolers. Speci fically\, our results allow us to select optimal parameters to reach “gi ant” negative values of an electrocaloric response from an ensemble of n on-interacting core-shell nanoparticles. A giant ECE\, such as cooling by 20 K\, could be very promising for advanced applications of ferroelectric nanocomposites in energy convertors and cooling systems.\n\nFigure 1. (a) Spherical ferroelectric NPs covered with a thin semiconducting shell and p laced in an isotropic dielectric polymer (b) Dependence of the EC temperat ure change $\\Delta T_EC$ on a quasi-static external electric field for na noparticles with a $BaTiO_3$ core covered with a rigid shell $ε_s$=300. T he curves are calculated for different values of mismatch strain between t he core and shell $u_m$ = –0\,4% (curve 1)\, 0 (curve 2)\, and +0.4% (cu rve 3). Shell thickness $\\Lambda$ = 4 nm\, and T = 293 K.\n\nAcknowledgem ents. A.N.M. acknowledges EOARD project 9IOE063 and related STCU partner p roject P751. R.H. acknowledges funding from the French National Research A gency through contract ANR-18-CE92-0052 “TOPELEC”. V.Y.R. acknowledges the support of COST Action CA17139. \n\n[1] X. Chen\, and C. Fang. Study of electrocaloric effect in barium titanate nanoparticle with core–shel l model. Physica B: Condensed Matter 415\, 14 (2013).\n[2] B. Li\, J. B. W ang\, X. L. Zhong\, F. Wang\, Y. K. Zeng\, and Y. C. Zhou. Giant electroca loric effects in ferroelectric nanostructures with vortex domain structure s. RSC Advances 3\, 7928 (2013). \n[3] Y. K. Zeng\, B. Li\, J. B. Wang\, X. L. Zhong\, W. Wang\, F. Wang\, and Y. C. Zhou. Influence of vortex doma in switching on the electrocaloric property of a ferroelectric nanoparticl e. RSC Advances 4\, 30211 (2014).\n[4] Z. Y. Chen\, Y. X. Su\, Z. D. Zhou \, L. S. Lei\, and C. P. Yang. The influence of the electrical boundary co ndition on domain structures and electrocaloric effect of PbTiO3 nanostruc tures. AIP Advances 6\, 055207 (2016).\n[5] F. Wang\, L. F. Liu\, B. Li\, Y. Ou\, L. Tian\, and W. Wang. Inhomogeneous electric-field–induced neg ative/positive electrocaloric effects in ferroelectric nanoparticles. EPL (Europhysics Letters) 117\, 57002 (2017).\n[6] C. Ye\, J. B. Wang\, B. Li \, X. L. Zhong\, Giant electrocaloric effect in a wide temperature range i n PbTiO3 nanoparticle with double-vortex domain structure. Sci. Rep. 8\, 2 93 (2018).\n[7] A. N. Morozovska\, E. A. Eliseev\, M. D. Glinchuk\, H. V. Shevliakova\, G. S. Svechnikov\, M. V. Silibin\, A. V. Sysa\, A. D. Yaremk evich\, N. V. Morozovsky\, and V. V. Shvartsman. Analytical description of the size effect on pyroelectric and electrocaloric properties of ferroele ctric nanoparticles. Phys. Rev. Materials 3\, 104414 (2019).\n[8] Yu. A. Barnakov\, I. U. Idehenre\, S. A. Basun\, T. A. Tyson\, and D. R. Evans. U ncovering the Mystery of Ferroelectricity in Zero Dimensional Nanoparticle s. Royal Society of Chemistry\, Nanoscale Adv. 1\, 664 (2019).\n\nhttps:// indico.bitp.kiev.ua/event/7/contributions/191/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/191/ END:VEVENT BEGIN:VEVENT SUMMARY:High-energy and very high-energy gamma-ray emission from the magne tar SGR 1900+14 neighbourhood DTSTART;VALUE=DATE-TIME:20201222T111000Z DTEND;VALUE=DATE-TIME:20201222T113000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-211@indico.bitp.kiev.ua DESCRIPTION:Speakers: Vadym Voitsekhovskyi (Astronomical Observatory of Ta ras Shevchenko National University of Kyiv)\nMagnetar wind nebulae (MWNe)\ , created by new-born millisecond magnetars\, and magnetar giant flares ar e PeVatron candidates and even potential sources of ultra high energy (E>1 018 eV) cosmic rays (UHECRs). Nonthermal high-energy (HE\, E>100 MeV) and very high-energy (VHE\, E>100 GeV) γ-ray emission from magnetars neighbou rhoods should be a promising signature of acceleration processes. We inves tigate a possibility of explaining HE and VHE γ-ray emission from the vic inity of the magnetar SGR 1900+14 by cosmic rays accelerated in a Supernov a remnant of a magnetar-related Supernova and/or in a MWN. Simulation of t he observed HE (the extended Fermi-LAT source 4FGL J1908.6+0915e) and VHE (the extended H.E.S.S. source candidate HOTS J1907+091 and the point-like HAWC TeV source 3HWC J1907+085) γ-ray emission\, spatially coincident wit h the magnetar SGR 1900+14\, was carried out in the framework of hadronic (pp collisions with a subsequent pion decay) and leptonic (inverse Compton scattering of low energy background photons by ultrarelativistic electron s) models. We show that under reasonable assumptions about parameters of t he circumstellar medium the observed γ-ray emission of Fermi-LAT 4FGL J19 08.6+0915e\, H.E.S.S. HOTSJ1907+091 and 3HWC J1907+085 sources may be expl ained or at least considerably contributed by a (still undetected) magneta r-connected Hypernova remnant and/or a MWN created by new-born millisecond magnetar with a large reserve of rotational energy Erot∼1052 erg.\n\nht tps://indico.bitp.kiev.ua/event/7/contributions/211/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/211/ END:VEVENT BEGIN:VEVENT SUMMARY:Thermoelectricity: from the iron arc of the epoch of Alessandro Vo lta to ferrofluids today DTSTART;VALUE=DATE-TIME:20201221T123000Z DTEND;VALUE=DATE-TIME:20201221T131500Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-208@indico.bitp.kiev.ua DESCRIPTION:Speakers: Andrey Varlamov (Istituto superconduttori\, material i innovativi e dispositivi (SPIN-CNR))\nI will start my talk with the revi ew of the exciting story of thermoelectricity in which were involved such famous scientists as Luigi Galvani\, Alessandro Volta\, Thomas Seebeck\, J ean Charles Athanase Peltier\, Walter Nernst\, William Tompson\, Nevil Mot t\, Lars Onsager\, philosopher Georg Wilhelm Hegel\, political figures li ke Napoléon Bonaparte. \n\nThen I will pass to the main concepts of therm odynamic and kinetic approaches to the description of thermoelectric and t hermomagnetic phenomena\, will discuss the cases of their giant manifestat ion. I will formulate the requirements for the materials necessary for pra ctical applications of thermoelectricity and present already available new materials. \n\nIn the final part of my talk I will shortly present the Fu ture Emergent Technologies European Project MAGENTA - MAGnetic nanoparticl e based ENergy materials for Thermoelectric device Applications (CEA – C NR – FIAT-DEMOCRITOS – …. ).\n\nhttps://indico.bitp.kiev.ua/event/7/ contributions/208/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/208/ END:VEVENT BEGIN:VEVENT SUMMARY:Bending-induced flexoelectric polarization and conductivity of low -dimensional transition metal dichalcogenides DTSTART;VALUE=DATE-TIME:20201221T133500Z DTEND;VALUE=DATE-TIME:20201221T135500Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-195@indico.bitp.kiev.ua DESCRIPTION:Speakers: Hanna Shevliakova (Department of Microelectronics\, Igor Sikorsky Kyiv Polytechnic Institute)\nBulk TMDs are typically non-pol ar centrosymmetric semiconductors with a relatively wide band gap ~(1.1 – 2) eV [1]\, however\, on transition from the bulk form to the nanoscal e additional orderings emerge [2\, 3]. The properties of low-dimensional ( LD) transition metal dichalcogenides (TMDs) with a chemical formula MX2 (M – metal Mo\, W\, Re\; X – chalcogen S\, Se\, Te) and Janus-compounds (JC) with a chemical formula MXY (X\, Y – chalcogens) can be changing in a broad range of properties varying from non-polar to ferroelectric\, and from direct-band semiconductor to metallic [4\, 5]. These opportunities o f tunability of polar and semiconducting properties are provided by contro lling factors\, such as composition\, doping\, and field effect. However\, known studies in this fields are mostly empirical and almost not systemat ized.\nRecently [6] we developed LGD-type theory for the description of po lar phenomena in LD-TMDs\, specifically explored flexoelectric origin of t he polarization induced by a spontaneous bending and by inversion symmetry breaking due to the interactions with substrate. This work is devoted to the establishment of correlation between polar and electronic properties o f LD-TMDs and JCs [7]. Using finite element modeling (FEM) we calculated t he elastic and electric fields\, flexoelectric polarization and free charg e density for a TMD (or JC) nanoflake placed on a rough gold substrate wit h a sinusoidal profile of the corrugation.\nAnalysis of FEM results obtain ed for the different flake thickness (varying from 10 layers to 300 nm) an d corrugation depth (varying from 0 to 50 nm)\, allows to corroborate the flexoelectric nature of the out-of-plane electric polarization and establi sh the unambiguous correlation between the polarization and static conduct ivity modulation caused by inhomogeneous elastic strains coupled with defo rmation potential and strain gradients\, which evolve in the nanoflake due to the adhesion between the flake surface and corrugated substrate.\nWe r evealed a pronounced maximum at the thickness dependences of the electron and hole conductivity of MoX2 and MXY nanoflakes placed on a substrate wit h a sinusoidal corrugation. Namely the conductivity is maximal for a (75 - 80) nm thick flakes placed on a gold substrate with the 4 nm corrugation height (see Fig. 1). This result opens the way for the nanoflakes geometry optimization towards significant improvement their polar and electronic p roperties\, which necessary for their advanced applications in nanoelectro nics and memory devices.\n\nThe work has received funding from the Nationa l Research Foundation of Ukraine (Grant application 2020.02/0027\, Contras t N 52/02.2020).\n\nFIGURE 1. Thickness dependence of the bending-induced relative static electron (a)\, and holes (b)\nconductivity at the top surf ace of a MoTe2 placed on a corrugated gold (Au) substrate. Nanoflake top\n and bottom surfaces reaction when it is placed at the “top” of the cor rugation are shown by red and\nblue symbols\, respectively\; and the nanof lake top reaction when it is placed the at the corrugation\n“slope” is shown by green curves. From [7].\n\n[1] S. Kang\, S. Kim\, S. Jeon\, W.-S . Jang\, D. Seol\, Y.-M. Kim\, J. Lee\, H. Yang\, and Y. Kim.\nAtomic-scal e symmetry breaking for out-of-plane piezoelectricity in two-dimensional t ransition\nmetal dichalcogenides. Nano Energy 58\, 57-62 (2019).\n[2] S. Y uan\, X. Luo\, H.L. Chan\, C. Xiao\, Y. Dai\, M. Xie\, and J. Hao. Room-te mperature\nferroelectricity in MoTe2 down to the atomic monolayer limit. N at. Commun. 10\, 1775 (2019).\n[3] K.-A.N. Duerloo\, Y. Li\, and E.J. Reed \, Structural phase transitions in two-dimensional Mo- and\nW-dichalcogeni de monolayers\, Nat. Commun. 5\, 4214 (2014).\n[4] D.W. Boukhvalov and M.I . Katsnelson. Enhancement of chemical activity in corrugated\ngraphene. J. Phys. Chem. C 113\, 14176 (2009).\n[5] S.V. Kalinin\, and V. Meunier. Ele ctronic flexoelectricity in low-dimensional systems. Phys.\nRev. B\, 77\, 033403 (2008).\n[6] A.N. Morozovska\, E.A. Eliseev\, G.I. Dovbeshko\, M.D. Glinchuk\, Y. Kim\, and S.V. Kalinin.\nFlexo-induced ferroelectricity in low dimensional transition metal dichalcogenides. Phys. Rev. B\n102\, 0754 17 (2020).\n[7] A. N. Morozovska\, E. A. Eliseev\, H. V. Shevliakova\, G. I. Dovbeshko\, M. D. Glinchuk\, Y. Kim\,\nand S. V. Kalinin. Correlation b etween corrugation-induced flexoelectric polarization and\nconductivity of low-dimensional transition metal dichalcogenides (http://arxiv.org/abs/20 11.09326)\n\nhttps://indico.bitp.kiev.ua/event/7/contributions/195/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/195/ END:VEVENT BEGIN:VEVENT SUMMARY:Compressibility and compactivity of bi-dispersive many-particle co nglomerations (liquid and granular mixtures) DTSTART;VALUE=DATE-TIME:20201222T153000Z DTEND;VALUE=DATE-TIME:20201222T155000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-188@indico.bitp.kiev.ua DESCRIPTION:Speakers: Andrii Spivak (Odesa State Environmental University) \nWe propose to use the apparatus of Kirkwood-Buff theory [1] in combinati on with Carnahan-Starling model [2] and Mansoori [3] equations of state t ogether with the relevant phenomenological information\, which obtained fr om the direct observations\, to describe compressibility and compactivity of bi-dispersive many-particle conglomerations (liquid [4] and granular mi xtures [5]). By use of above mentioned approach we found the possibility t o describe substantiate empirical data in the full range of values of the volume (or molar) fraction. A good coincidence between theoretical and rel evant experimental data has been outlined.\n\n[1]. Kirkwood J.G.\, Buff F. P. The statistical mechanical theory of solutions. I. J. Chem. Phys. 19(6) \, 774-777 (1951) https://doi.org/10.1063/1.1748352\n[2]. Carnahan N.F.\, Starling K.E. Equation of state for nonattracting rigid spheres. I. J. Che m. Phys. 51(2)\, 635-636. (1969) https://doi.org/10.1063/1.1672048\n[3]. M ansoori G.A.\, Carnahan N.F.\, Starling K.E.\, Leland jr. T.W. Equilibrium Thermodynamic Properties of the Mixture of Hard Spheres. J. Chem. Phys. 5 4(4)\, 1523-1525 (1971) https://doi.org/10.1063/1.1675048\n[4]. Aliotta F .\, Gapiński J.\, Pochylski M.\, Ponterio R.C.\, Saija F.\, Salvato G. Ex cess compressibility in binary liquid mixtures. J. Phys. Chem. 126(22)\, 2 24508 (2007) https://doi.org/10.1063/1.2745292\n[5]. Pilliteri S.\, Lumay G.\, Opsomer E.\, Vandewalle N. From jamming to fast compaction dynamics i n granular binary mixtures. Sci. Rep. 9(1)\, 7281 (2019) https://doi.org/1 0.1038/s41598-019-43519-6\n\nhttps://indico.bitp.kiev.ua/event/7/contribut ions/188/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/188/ END:VEVENT BEGIN:VEVENT SUMMARY:Circular stripe domains in a vertically stacked magnetic heterostr uctures DTSTART;VALUE=DATE-TIME:20201223T084000Z DTEND;VALUE=DATE-TIME:20201223T090000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-196@indico.bitp.kiev.ua DESCRIPTION:Speakers: Oleksandr Zaiets (Taras Shevchenko National Universi ty of Kyiv)\nMagnetic vortex is known to form a ground state of magnetic n anodisk with easy-plane anisotropy [1]. A perpendicularly magnetized disk in a nanostack can also support the vortex state due to the interlayer exc hange coupling with the vortex state thick layer [2]. \n\nFig.1: Phase dia gram of different states on Co disk. The following parameters of the Co di sk were used in OOMMF simulations: disk radius $R = 500$ nm\, exchange con stant $A = 2\\times10^{-11}$ J/m\, saturation magnetization $Ms = 5\\times 10^5$ A/m\, easy-normal anisotropy $K = 2\\times10^5$ J/m$^3$. \n\nHere we predict formation of circular stripe domains in the cylinder nanopillar o f vertically stacked magnetic heterostructure. Using OOMMF micromagnetic s imulations [3] we model the three-layer heterostructure where the topologi cal magnetization texture is imprinted into an out-of-plane magnetized mat erial through stacking three layers with in-plane magnetization (Py master layer)\, nonmagnetic material (Pd spacer layer) and out-of-plane magnetiz ation (Co slave layer\, the sample). The phase diagram of equilibrium magn etisation states in the sample disk is computed in a wide range of the cou pling parameter for different thicknesses of the sample layer (see Fig.1): (i) The cone phase is realized for a weak coupling\; within this phase th e cone-state light vortex has a structure\, similar to ones in easy-plane magnets under the action of perpendicular magnetic field [4]. (ii) The opp osite limit case of strong coupling results to the vortex phase\, which st ructure mimics the master layer vortex texture. (iii) The appearance of th e new phase with the circular stripe domains is a key finding of the curre nt study. This circular stripe phase is realized for the intermediate coup ling parameters. The modulation instability of the cone state is triggered by the nonlocal magnetostatic interaction\, which results in the generati on of the stable equilibrium magnetization texture in the form of circular stripes domains. The number of stripes is controlled by both coupling par ameters and the sample thickness. The phase transition between different s tates is described analytically using a simple Ansatz model and correspond s to the full scale micromagnetic simulations. The variety of magnetizatio n textures with well-defined phases corresponds to the experimentally obse rved vortex and donut states in [2].\nThe possibility to switch between di fferent topologically nontrivial states allows for engineering magnetic te xtures with possible applications in spintronic devices.\n\nReferences\n[1 ] A. Hubert and R. Schäfer\, Magnetic domains: the analysis of magnetic m icrostructures\, Springer (2009)\n[2] R. Streubel et al\, Scientific Repor ts 5\, 8227 (2015) \n[3] Object Oriented MicroMagnetic computing Framework (OOMMF) \n[4] B. A. Ivanov and D. D. Sheka\, Low Temperature Physics 21\, 881 (1995)\n\nhttps://indico.bitp.kiev.ua/event/7/contributions/196/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/196/ END:VEVENT BEGIN:VEVENT SUMMARY:Occupation-conservation transition in a quantum two-level system DTSTART;VALUE=DATE-TIME:20201221T144000Z DTEND;VALUE=DATE-TIME:20201221T150000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-190@indico.bitp.kiev.ua DESCRIPTION:Speakers: Oleh Ivakhnenko (B. Verkin ILTPE of NASU)\nWhen we d rive quantum two-level systems (or qubits) by periodical signals\, we obta in repeatedly Landau-Zener-Stückelberg-Majorana (LZSM) transitions\, whic h relates to the tunneling in qubits [1]. Recent interest for studying the se repeated transitions is caused by the success in creation of the first quantum computing machines which are based on different types of connected driven qubits. We describe a transfer matrix (TM) approach [2]\, and its area of usability\, for a single LZSM transition which started from a supe rpositional state. As the result\, we obtain a formula for describing the final occupation probability with any superpositional initial state. We co nsider three types of a single transition\, with: 1. Constructive interfer ence\, 2. Destructive interference\, and 3. Occupation-conservation transi tion. The last one allows us to save the same occupation probability as be fore the transition. TM can also be used for describing repetitive transit ions by using the result of the current transition as the initial conditio n for the next one. Previously in Ref. [3] the "transitionless transitions " in qubits were studied\, there the author described only the case when i nitially a qubit was not in any superpositional state\, but rather only in one of the basis states. In Fig. 1 we demonstrate constructive and destr uctive transition in comparison with numerical and analytic solution on th e left side and occupation conservation case in the right panel\, where al so we demonstrated the range of possible final occupation probabilities.\n \nFig. 1. (left) Constructive and destructive LZSM transitions\, (right) O ccupation-conservation transition\, where the probability after passing th e avoided-level crossing is exactly the same as it was initially. Both pan els are plotted with the same initial conditions $P_{+i}=0.2$\, the same p arameters defining the transition probability\, if starting from the groun d state\, $P_{LZSM}=0.081$\, and with the initial phase difference $\\phi_ i$ being different in each case.\n\nAcknowledgment:\nResearch of O.V.I. an d S.N.S. is sponsored by the Army Research Office and is accomplished unde r Grant Number W911NF-20-1-0261.\n\n[1] O.V. Ivakhnenko\, S.N. Shevchenko\ , and F. Nori «Landau-Zener-Stückelberg-Majorana (LZSM) transitions for interferometry and quantum control»\, in preparation.\n[2] B. Damski and W. H. Zurek\, «Adiabatic-impulse approximation for avoided level crossing s: from phase-transition dynamics to Landau-Zener evolutions and back agai n»\, Phys. Rev. A 73\, 063405 (2006).\n[3] M. V. Berry\, «Transitionless quantum driving»\, J. Phys. A: Math. Theor. 42\, 365303 (2009).\n\nhttps ://indico.bitp.kiev.ua/event/7/contributions/190/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/190/ END:VEVENT BEGIN:VEVENT SUMMARY:Detecting geometric measure of entanglement of graph states on qua ntum computer DTSTART;VALUE=DATE-TIME:20201222T135000Z DTEND;VALUE=DATE-TIME:20201222T141000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-192@indico.bitp.kiev.ua DESCRIPTION:Speakers: Khrystyna Gnatenko (Ivan Franko National University of Lviv\, Department for Theoretical Physics)\nGraph states generated by o perator of evolution with Ising Hamiltonian are studied. The geometric mea sure of entanglement of the states is quantified analytically. For this pu rpose relation of the geometric measure of entanglement with the mean valu e of the spin is used (the relation was obtained in [1]). Also\, quantum protocol for preparing graph states of spin system with Ising interactio n is constructed. The geometric measure of entanglement of the states is d etecting on the IBM's quantum computers.\nWe obtained that entanglement of spin with other spins in the graph state depends on the graph properti es\, namely it depends on the degree of vertex that corresponds to the spi n.\n\n\n[1] A. M. Frydryszak\, M. I. Samar\, V. M. Tkachuk\, Eur. Phys. J. D 71\, 233 (2017).\n\nhttps://indico.bitp.kiev.ua/event/7/contributions/1 92/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/192/ END:VEVENT BEGIN:VEVENT SUMMARY:Two-phase structure of ultralight dark matter with $\\psi^6$ self- interaction. DTSTART;VALUE=DATE-TIME:20201222T103000Z DTEND;VALUE=DATE-TIME:20201222T105000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-184@indico.bitp.kiev.ua DESCRIPTION:Speakers: M. V. Khelashvili (Bogolubov Institute for Theoretic al Physics)\nThe ultralight dark matter (ULDM) model (also known as fuzzy dark matter or Bose-Einstein condensate dark matter) is one of alternative s to the cold dark matter (CDM) paradigm. It suggests that the dark matte r particles are ultralight bosons with a tiny mass order of $10^{-22}$ eV\ , so that their de Broglie wavelength is of kiloparsec scale\, that helps to resolve CDM tensions on the small scales. We consider ultralight scalar bosons condensate with $\\psi^6$ self-interaction\, which has a noticeabl e effect on the dark matter density distribution in highly dense regions\, such as a central core of galactic dark matter halo or overlap of dark ma tter halo during the galaxies collision. At the same time\, a contribution of tree-particles interaction is negligible in an outer part of the galac tic dark matter halo and intergalactic medium. Thus all ULDM predictions o n the large scales remain valid for the $\\psi^6$ model\, which\, in turn\ , coincide with CDM predictions on these scales and are in agreement with observations. From the detailed analysis of thermodynamic characteristics of ULDM with $\\psi^6$ self-interaction\, we find the existence of two ph ases of dark matter separated by instability region in the (high density) core of dark matter halo.\n\nhttps://indico.bitp.kiev.ua/event/7/contribut ions/184/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/184/ END:VEVENT BEGIN:VEVENT SUMMARY:Resonant interferometry and spectroscopy of a double-quantum-dot system DTSTART;VALUE=DATE-TIME:20201221T150000Z DTEND;VALUE=DATE-TIME:20201221T152000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-197@indico.bitp.kiev.ua DESCRIPTION:Speakers: Artem Ryzhov (ILTPE\, Ukraine)\nA double quantum dot system is a mesoscopic system with quantum properties in a semiconductor. It is one of the realizations of a two-qubit system. An external periodic al driving of parameters of the system with avoided-level crossing causes nonadiabatic transitions and results in coherent interference fringes in t he system’s occupation probabilities. For qubits with repelling energy l evels\, such interference\, named after Landau-Zener-Stückelberg-Majorana \, displays arc-shaped resonance lines. We demonstrate that the form of th e resonances for systems without avoided-level crossings\, such as the dou ble quantum dot\, change to harp-shaped one. We consider both stationary s tates and the dynamics\, for which we solve the Lindblad equation. The for m of the resonances can be used for system spectroscopy\, which is importa nt for potential applications of double quantum dots\, such as multiple-el ectron transistors\, solar cells\, quantum computing.\n\nAcknowledgment.\n Research of A.I.R. and S.N.S. is sponsored by the Army Research Office and is accomplished under Grant Number W911NF-20-1-0261.\n\nhttps://indico.bi tp.kiev.ua/event/7/contributions/197/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/197/ END:VEVENT BEGIN:VEVENT SUMMARY:Probing and manipulating valley coherence of dark excitons in WSe$ _2$ monolayer DTSTART;VALUE=DATE-TIME:20201223T070000Z DTEND;VALUE=DATE-TIME:20201223T074000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-169@indico.bitp.kiev.ua DESCRIPTION:Speakers: Artur Slobodeniuk (Charles University)\nMonolayers o f semiconducting transition metal dichalcogenides are two-dimensional dire ct-gap systems that host tightly-bound excitons with an internal degree of freedom corresponding to the valley of the constituting carriers. Strong spin-orbit interaction and the resulting ordering of the spin-split subban ds in the valence and conduction bands makes the lowest-lying excitons in WX$_2$ (X being S or Se) spin-forbidden and optically dark. This results i n their long lifetime\, making them potentially interesting for valleytron ics. With polarization-resolved photoluminescence experiments performed on a WSe$_2$ monolayer encapsulated in a hexagonal boron nitride\, we demons trate how the intrinsic exchange interaction in combination with the appli ed in-plane and perpendicular magnetic fields enables one to probe and man ipulate the valley degree of freedom of the dark excitons.\n\nhttps://indi co.bitp.kiev.ua/event/7/contributions/169/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/169/ END:VEVENT BEGIN:VEVENT SUMMARY:Surface waves on resonant anisotropic metasurfaces DTSTART;VALUE=DATE-TIME:20201223T074000Z DTEND;VALUE=DATE-TIME:20201223T080000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-201@indico.bitp.kiev.ua DESCRIPTION:Speakers: Oleh Yermakov (Department of Сomputer Physics\, V. N. Karazin Kharkiv National University)\nThis work presents the results of theoretical and experimental studies and control of the properties (dispe rsion\, polarization\, phase and spatial distribution\, directivity\, opti cal spin) of surface electromagnetic waves localized on anisotropic resona nt metasurfaces in the optical\, near-IR and microwave ranges.\n\nhttps:// indico.bitp.kiev.ua/event/7/contributions/201/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/201/ END:VEVENT BEGIN:VEVENT SUMMARY:Magnetic field-induced phase transitions in antiferromagnetic ring s DTSTART;VALUE=DATE-TIME:20201223T092000Z DTEND;VALUE=DATE-TIME:20201223T094000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-200@indico.bitp.kiev.ua DESCRIPTION:Speakers: Yelyzaveta A. Borysenko (Taras Shevchenko National U niversity of Kyiv\, 01601 Kyiv\, Ukraine)\nAn emerging field of curvilinea r magnetizm brings about new geometry-induced phenomena in usual magnetic materials\, balancing between fundamental research\, material sciences and technologies [1]. Modern technological advances allow to consider antifer romagnets (AFMs) as promising building blocks for spintronic and spin-orbi tronic applications [2]. In this respect\, curvilinear spin chains with AF M coupling are of fundamental interest as simplest systems possessing inte rplay between geometry and magnetic subsystem.\nHere\, we analyze the grou nd states of AFM ring with the nearest-neighbour Heisenberg exchange and s trong single-ion anisotropy in the presence of external magnetic field\, w hich is normal to the ring plane. We consider collinear two-sublattice 1D curved AFM spin chain with even number of spins. The hard axis of anisotro py is oriented tangentially to the chain. Within the classical continuum a pproach [3]\, its magnetic state is determined by the vector fields of Né el and ferromagnetism. In the ground state\, the Néel vector is oriented perpendicularly to the ring plane (binormal state\, see Fig.1) [3\,4]. The magnetic field applied along the ring normal allows to observe spin-flop and spin-flip orientational phase transitions. We determine the dependency of spin-flop and spin-flip transition fields on the ring curvature. There is a critical curvature ($\\kappa_c$)\, separating two topologically diff erent ground states above spin-flop. The first one with the Néel order pa rameter within the normal plane is mainly determined by the anisotropy at small curvatures (normal state\, see Fig.1). The second ground state at la rge curvatures is represented by oninon ordering of the Néel vector (onio n state\, see Fig.1). With the applied fields $h>h^0$\, Néel order parame ter vanishes (ferromagnetic state). The phase diagram of AFM as a function of applied field intensity is presented in Fig.1: all analytical predicti ons are well-confirmed by the SLaSi spin-lattice simulations [5].\n\nFig.1 : phase-diagram.jpg should be here\, with \ncaption: "Phase diagram of eq uilibrium magnetization states of antiferromagnetic ring\; $h^{sf}_0$ is t he spin-flop transition field in the bulk\, $\\kappa$ is the ring curvatur e\, $\\ell = 5 a_0$ is the magnetic length\, with $a_0$ being the lattice constant. Symbols correspond to spin-lattice simulation data\, solid lines describe analytically calculated boundary between states"\n\n[1] E.Vedmed enko et al\, Journal of Physics D: Applied Physics 53\, 453001(2020).\n[2] V. Baltz et al\, Reviews of Modern Physics 90\, 015005 (2018)\n[3] O. V. Pylypovskyi et al\, Nano Letters 20\, 8157 (2020)\n[4] S. Castillo-Sepulve da et al\, Physical Review B 96\, 024426 (2017)\n[5] [SLaSi spin–lattice simulations package]\n\nhttps://indico.bitp.kiev.ua/event/7/contributions /200/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/200/ END:VEVENT BEGIN:VEVENT SUMMARY:Excess Thermodynamic Properties of Binary Liquid Mixtures of Butan ol Isomers with Di-n-Butyl Ether at 298.15 K\, 0.1 MPa DTSTART;VALUE=DATE-TIME:20201223T124500Z DTEND;VALUE=DATE-TIME:20201223T130500Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-199@indico.bitp.kiev.ua DESCRIPTION:Speakers: Leon Engelbrecht (University of Cagliari\, Italy)\nB inary liquid mixtures of alcohols and ethers are of importance as potentia l biofuels or additives for internal combustion engines\,[1] and have also attracted fundamental interest as model liquid systems containing one com ponent (the alcohol) that can strongly self-associate through hydrogen bon ding (HB)\, and one that cannot self-associate via HBs (ether)\, yet can i nteract strongly with the former as HB acceptor.[2] The excess thermodynam ic properties of these mixtures\, specifically the excess molar enthalpies and volumes (HE and VE)\, have been extensively measured.[1-3] Butanol is omer + di-*n*-butyl ether (DBE) binary mixtures\, in particular\, show int eresting volumetric differences\, with VE changing from negative (1- and * iso*-butanol) to positive (2- and *tert*-butanol) with increasing butanol alkyl group branching. Representative 1- and 2-butanol + DBE mixtures were studied\, for the first time\, by atomic-resolution classical Molecular D ynamics (MD) computer simulations. The simulations reveal decided differen ces in the degree of self-association of the two butanol isomers and suppo rt existing interpretations of the HE and VE in a general sense\, but als o suggest that more subtle differences in H-bonded topologies may contribu te significantly to the anomalous volumetric properties of these mixtures. [4]\n\nFig. 1. MD computer simulation configurations of equimolar mixtures of 1- or 2-butanol with DBE. Ether molecules are omitted and hydroxyl (-O H) groups shown using a space-filling (red and white spheres) representati on in order to highlight the differences in HB topologies. Simulation cell edges are shown in blue.\n\nReferences:\n[1] (a) Rezanova\, E. N.\; Kamme rer\, K.\; Lichtenthaler\, R. N. J. Chem. Eng. Data 1999\, 44\, 1235-1239. (b) Alaoui\, F. E. M.\; Montero\, E. A.\; Brazile\, J. -P.\; Aguilar\, F. \; Boned\, C. J. Chem. Thermodynamics\, 2011\, 43\, 1768-1774.\n[2] (a) Mo toyama\, I.\; Jarboe\, C. H. J. Phys. Chem. 1967\, 71 (8)\, 2723-2726. (b) Pathak\, G.\; Pradhan\, S. Proc. Indian Acad. Sci. (Chem. Sci.) 1988\, 10 0 (6)\, 519-523. (c) Lechter\, T. M.\; Govender\, P. U. Fluid Phase Equili bria\, 1997\, 140\, 207-220.\n[3] (a) Patil\,K. R.\; Pathak\, G.\; Pradhan \, S. D. Proc. Indian Acad. Sci. (Chem. Sci.) 1989\, 101 (5)\, 443-447. (b ) Kammerer\, K.\; Licthenthaler\, R. N. Thermochim. Acta 1998\, 310 (1-2)\ , 61-67. (c) Bernazzani\, L.\; Carosi\, M. R.\; Duce\, C.\; Gianni\, P.\; Mollica\, V. J. Solution Chem. 2006\, 35 (11)\, 1567-1585.\n[4] Engelbrech t\, L.\; Farris\, R.\; Vasiliu\, T.\; Demurtas\, M.\; Laaksonen\, A.\; Pir as\, A.\; Cesare Marincola\, F.\; Porcedda\, S.\; Mocci. F. Submitted for publication.\n\nhttps://indico.bitp.kiev.ua/event/7/contributions/199/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/199/ END:VEVENT BEGIN:VEVENT SUMMARY:Dynamics of micro-organisms controlled by liquid crystals DTSTART;VALUE=DATE-TIME:20201222T144500Z DTEND;VALUE=DATE-TIME:20201222T153000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-213@indico.bitp.kiev.ua DESCRIPTION:Speakers: Oleg Lavrentovich (Advanced Materials and Liquid Cry stal Institute\, Department of Physics and Materials Science Graduate Prog ram\, Kent State University)\nMicroscale active systems such as swarms of swimming bacteria and cell tissues demonstrate fascinating dynamics that c an potentially be used in applications ranging from micro-robotics to rege nerative medicine. Control of this dynamics in isotropic media such as wat er is difficult. We describe an approach in which instead of an isotropic medium\, the dynamics of micro-organisms is guided by a liquid crystal. A n example with a droplet of an active bacterial suspension shows an immedi ate benefit of such a replacement: when placed in an isotropic fluid\, the droplet experiences random Brownian motion\, but once the medium becomes a nematic liquid crystal\, the droplet acquires an ability to swim unidire ctionally along a prescribed trajectory [1]. Other examples of liquid crys tal control over the dynamics of microscopic objects include dynamic swarm s of swimming bacteria [2-4] and living tissues formed by human dermal fib roblasts [5]. Director gradients and topological defects impact the biolog ical microstructures most strongly\, causing spatial variation of bacteria l concentration and cell phenotype and shaping irreversible active flows. The physical mechanisms are shaped by the nontrivial effect of the orient astional order of a liquid crystal on the interactions of dynamic active u nits. The control of active matter by patterned liquid crystals might res ult in new approaches to harness the energy of collective motion for micro -robotic\, biomechanical\, biomedical\, and sensing applications. \n\nThe work is supported by NSF DMR-1905053\, CMMI-1663394\, and DOE DE-SC0019105 grants. \n\n[1] M. Rajabi\, B. Hend\, T. Turiv\, and O. D. Lavrentovich\, Directional self-locomotion of active droplets enabled by nematic environ ment\, Nature Physics\, https://doi.org/10.1038/s41567-41020-01055-41565 ( 2020).\n[2] C. Peng\, T. Turiv\, Y. Guo\, Q.-H. Wei\, and O. D. Lavrentovi ch\, Command of active matter by topological defects and patterns\, Scienc e 354\, 882-885 (2016).\n[3] T. Turiv\, R. Koizumi\, K. Thijssen\, M. M. G enkin\, H. Yu\, C. Peng\, Q.-H. Wei\, J. M. Yeomans\, I. A. Aranson\, A. D oostmohammadi\, and O. D. Lavrentovich\, Polar jets of swimming bacteria c ondensed by a patterned liquid crystal\, Nature Physics 16\, 481–487 (20 20).\n[4] R. Koizumi\, T. Turiv\, M. M. Genkin\, R. J. Lastowski\, H. Yu\, I. Chaganava\, Q.-H. Wei\, I. S. Aranson\, and O. D. Lavrentovich\, Contr ol of bacterial swirls by spiral nematic vortices: Transition from individ ual to collective motion and contraction\, expansion\, and stable circulat ion of bacterial swirls\, Physical Review Research 2\, 033060 (2020).\n[5] T. Turiv\, J. Krieger\, G. Babakhanova\, H. Yu\, S. V. Shiyanovskii\, Q. Wei\, -H.\, M.-H. Kim\, and O. D. Lavrentovich\, Topology control of human fibroblast cells monolayer by liquid crystal elastomer\, Science Advances 6\, eaaz6485 (2020).\n\nhttps://indico.bitp.kiev.ua/event/7/contributions /213/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/213/ END:VEVENT BEGIN:VEVENT SUMMARY:Neutron Star Cooling Within the Equation of State With Induced Sur face Tension DTSTART;VALUE=DATE-TIME:20201222T085000Z DTEND;VALUE=DATE-TIME:20201222T091000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-165@indico.bitp.kiev.ua DESCRIPTION:Speakers: Stefanos Tsiopelas (University of Coimbra)\nWe study the thermal evolution of neutron stars described within the equation of s tate with induced surface tension (IST) that reproduces properties of norm al nuclear matter\, fulfills the proton flow constraint\, provides a high- quality description of hadron multiplicities created during the nuclear-nu clear collision experiments\, and it is equally compatible with the constr aints from astrophysical observations and the GW170817 event. The model fe atures strong direct Urca processes for the stars above $1.91~M_{\\odot}$. The IST equation of state shows very good agreement with the available co oling data\, even without introducing nuclear pairing. We also analysed th e effect of the singlet proton/neutron and triplet neutron pairing on th e cooling of neutron stars of different mass. We show that the description of the compact object in the center of the Cassiopeia A does not necessar ily require an inclusion of neutron superfluidity and/or proton supercondu ctivity. Our results indicate that data of Cassiopeia A can be adequately well reproduced by a $1.66~M_{\\odot}$ star with an atmosphere of light el ements. Moreover\, the IST EoS reproduces each of the observational datase ts for the surface temperature of Cassiopeia A either by a rapidly cooling $\\sim$ $1.955~M_{\\odot}$ star with paired and unpaired matter or by a $ 1.91 M_{\\odot}$ star with the inclusion of neutron and proton pairings in the singlet channel.\n\nhttps://indico.bitp.kiev.ua/event/7/contributions /165/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/165/ END:VEVENT BEGIN:VEVENT SUMMARY:On relaxation processes in plasma DTSTART;VALUE=DATE-TIME:20201222T155000Z DTEND;VALUE=DATE-TIME:20201222T161000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-203@indico.bitp.kiev.ua DESCRIPTION:Speakers: Oleh Hrinishin ()\nThe plasma is considered in a gen eralized Lorentz model which contrary to standard one assumes that ions fo rm an equilibrium system. Following to Lorentz it is neglected by electron -electron and ion-ion interactions. Relaxation of the electron energy and momentum densities is investigated in spatially uniform states of complete ly ionized plasma in the presence of small constant and spatially homogene ous external electric field. The kinetic equation is given by the formula: \n$\\left[{\\partial _t}{{\\rm{f}}_p}(t) = - {F_n}\\frac{{\\partial {{\\r m{f}}_p}(t)}}{{\\partial {p_n}}} + {I_p}({{\\rm{f}}_{p'}}(t))\\right]$\, (${F_n} = - e{E_n}$\, $\\int {{d^3}p{{\\rm{f}}_p}(t) = n} $ )\, (1)\nwhere ${E_n}$ is external electric field\, $ - e$ is charge of an electron\, $n$ is electron density. Perturbation theory is created in ter ms of spectral theory of operator of collision integral ${\\bf{K}}$\, whic h could be defined as ${\\bf{K}}{a_p} = - w_p^{ - 1}{I_p}({w_{p'}}{a_{p'} })$ (${w_p}$ is Maxwell distribution\; ${I_p}({w_{p'}}) = 0$). Linear oper ator ${\\bf{K}}$ is a symmetric and positively defined one. Complete ortho normal system of its own functions ${g_{ip}}$ could be used to find soluti ons of kinetic equation (1) as series by mods:\n${{\\rm{f}}_p} = {w_p}(1 + {g_p})$\, ${g_p} = \\sum\\limits_i {{c_i}{g_{ip}}} $. (2)\nWe use ir reducible polynomials as our own functions. The scalar ${A_p}$ and vector ${B_p}{p_l}$ eigenfunctions and corresponding eigenvalues ${\\lambda _{\\\ ,T}}$\, ${\\lambda _u}$ play a decisive role among its own functions\n${\\ bf{K}}{A_p} = {\\lambda _{\\\,T}}{A_p}$\, ${\\bf{K}}{B_p}{p_l} = {\\l ambda _u}{B_p}{p_l}$ ($\\langle {A_p}{\\varepsilon _p}\\rangle \\ equiv 3n/2$\, $\\langle {B_p}{\\varepsilon _p}\\rangle \\equiv 3n/2$). (3)\nIt is convenient to investigate the relaxation processes in the syst em in terms of average electron energy $\\varepsilon $ and momentum ${\\pi _l}$ densities. It is established that their evolution is exact described at all times by scalar and vector modes\n$\\left[\\varepsilon = {\\varep silon _0} + {c_T}3n/2\\right]$\, $\\left[{\\pi _l} = mn{c_{{u_l}}}\\right] $\, (${\\varepsilon _0} \\equiv 3nT/2$)\, (4)\nwhere ${c_T}$\, ${c_{ {u_l}}}$ – coefficients in series (2) with its eigenfunctions ${A_p}$\, ${B_p}{p_l}$ ($m$ – electron mass\, ${T_0}$ – ion system temperature) . It is proved that quantities $\\varepsilon $ і ${\\pi _l}$ at all times and for an arbitrary external electric field ${E_n}$ satisfy the equation :\n$\\left[{\\partial _t}{\\pi _l} = n{F_l} - {\\lambda _u}{\\pi _l}\\righ t]$\, $\\left[{\\partial _t}\\varepsilon = \\frac{1}{m}{\\pi _l}{F_l} - {\ \lambda _{\\\,T}}(\\varepsilon - {\\varepsilon _0})\\right]$. (5)\nThe re sults (4)\, (5) were found by using irreducible tensors as eigenfunctions of the operator ${\\bf{K}}$. Formulas (5) show that eigenvalues ${\\lambda _{\\\,T}}$\, ${\\lambda _u}$ describe relaxation process in the absence o f external electric field \n$\\varepsilon \\to \\varepsilon_0$\, when ${t\ \gg\\tau_{T}}$ and $\\pi _l \\to 0$\, when ${t\\gg\\tau_{u}}$\, (${\\tau _ T} \\equiv 1/{\\lambda _{\\\,T}}$\, ${\\tau _u} \\equiv 1/{\\lambda _u}$). (6)\nIn terms of temperature $T$ and velocity ${u_l}$ of electron system \n$\\varepsilon \\equiv 3nT/2 + mn{u^2}/2$\, ${\\pi _l} \\equiv mn{u_ l}$ (7)\nequations (5) take the form\n ${\\partial _t}T = - {\\lambda _ T}(T - {T_0}) + (2{\\lambda _u} - {\\lambda _T})m{u^2}/3$\, ${\\pa rtial _t}{u_n} = - {\\lambda _u}{u_n} + \\frac{1}{m}{F_n}$ (8)\nThese equ ations are exact and valid at all times and arbitrary electric field. The first one does not contains the electric field. At equilibrium equation (8 ) gives \n${u_l}(t)\\mathop = \\limits_{t > > {\\tau _T}\,{\\tau _u}} u_ l^{eq}$\, $u_l^{eq} = - \\nu {E_l}$\, $\\nu \\equiv \\frac{e }{{m{\\lambda _u}}}$\; $j_l^{eq} = \\sigma {E_l}$\, $\\sigma \\equiv \\frac{{{e^2}n}}{{{\\lambda _u}}}$\; \n$T(t)\\mathop = \\limit s_{t > > {\\tau _T}\,{\\tau _u}}{T^{eq}}$\, ${T^{eq}} = {T_0} + \\Delta T $\, $\\Delta T \\equiv \\frac{{{e^2}(2{\\lambda _u} - {\\lambda _T})}}{{3m {\\lambda _T}\\lambda _u^2}}{E^2}$ (9)\nThe expression for the mobility of electrons $\\nu$ and the plasma conductivity $\\sigma $ in (9) are exact. The last formula accurately describes the effect of temperature differenc es between the electron and ion components of the plasma in equilibrium in the presence of an electric field. This effect was previously discussed i n [2] as an approximate result and without accuracy control. \n\n[1] Sokol ovsky А.I.\, Sokolovsky S.A.\, Нrinishyn O.A. On relaxation processes in a completely ionized plasma. East European Journal of Physics. Vol. 3 (20 20). P. 19-30\; doi.org / 10.26565/2312-4334-2020-3-03.\n[2] Smirnov В.М . Kinetika elektronov v gazakh i kondensirovannykh sistemakh. UFN Vol. 17 2 (12) (2002). – P. 1411-1445 (in Russian).\n\nhttps://indico.bitp.kiev. ua/event/7/contributions/203/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/203/ END:VEVENT BEGIN:VEVENT SUMMARY:Multiscale simulation methods and their applications in nucleic ac id studies DTSTART;VALUE=DATE-TIME:20201223T120000Z DTEND;VALUE=DATE-TIME:20201223T124500Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-209@indico.bitp.kiev.ua DESCRIPTION:Speakers: Francesca Mocci (Chemistry and Geological Science De partment\, University of Cagliari)\nAfter almost seventy years from the di scovery of DNA double helix structure\, we know very much about nucleic ac id organization and functions. However\, there are still many structural a nd dynamical features - at different spatial and time scales - that have t o be understood better. Molecular simulations are essential to understand many properties at the molecular level. With a fast increase in the comput er power together with method and software development\, systems over incr easing sizes and longer and longer timescales can be simulated. However\, studies of DNA at the atomistic level have a practical maximum size allowi ng a few nucleosome core particles\, on the microsecond time scale to be s tudied. To reach larger spatial and longer temporal time scales\, necessar y when studying many of the biological problems involving DNA (e.g. those connected to DNA flexibility\, or to chromatin folding etc.) all-atom simu lations are far too expensive. It is necessary to coarsen the description of the system of interest\, by removing many details non-relevant to the p henomenon under investigation [1-4]. In this talk I will present selected coarse-grain (CG) models\, some of which can be applied to the double heli x conformation as well as to other nucleic acid structural motifs found in the cells\, like DNA quadruplexes [5-6]. Special attention will be given to the methods that can be used to study the counter-ions interactions wit h this highly charged poly-ion.\n\nReferences:\n[1] Mocci F\, Laaksonen A (2012). Insight into nucleic acid counterion interactions from inside mole cular dynamics simulations is “worth its salt”. Soft Matter\, 8\, 9268 -9284\n[2] Potoyan DA\, Savelyev A\, Papoian G A (2013) Recent successes i n coarse-grained modeling of DNA. WIREs Computational Molecular Science\, 3\, 69-8\n[3] Dans PD\, Walther J\, Gómez H\, Orozco M (2016) Multiscale simulation of DNA\, Current Opinion in Structural Biology\, 37\, 29-45\n[4 ] Sun T\, Mirzoev A\, Minhas V\, Korolev N\, Lyubartsev AP\, Nordenskiöld L (2019) \, A multiscale analysis of DNA phase separation: from atomistic to mesoscale level\, Nucleic Acids Research\, 47:11\, 5550–5562\,\n[5] Rebič M\, Mocci F\, Lyubartsev AP\, Uličný J\, Laaksonen A (2017) Coars e-Grained Simulation of Rodlike Higher-Order Quadruplex Structures at Diff erent Salt Concentrations ACS Omega 2 (2)\, 386-396\n[6] Rebič M\, Mocci F\, Laaksonen A\, Uličný J (2015) Multiscale simulations of human telome ric G-quadruplex DNA. The Journal of Physical Chemistry B 119 (1)\, 105-11 3\n\nhttps://indico.bitp.kiev.ua/event/7/contributions/209/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/209/ END:VEVENT BEGIN:VEVENT SUMMARY:Lambda spin polarization in QGP. DTSTART;VALUE=DATE-TIME:20201222T123000Z DTEND;VALUE=DATE-TIME:20201222T125000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-166@indico.bitp.kiev.ua DESCRIPTION:Speakers: Rajeev Singh (Institute of Nuclear Physics Polish Ac ademy of Sciences)\nMeasurements made recently by the STAR collaboration s how that the Lambda hyperons produced in relativistic heavy-ion collisions are subject to global spin polarization with respect to an axis coinciden t with the axis of rotation of the produced matter. Recently formulated fo rmalism of relativistic hydrodynamics with spin\, which is a generalizatio n of the standard hydrodynamics\, is a natural tool for describing the evo lution of such systems. This approach is based on the conservation laws an d the form of the energy-momentum tensor and spin tensor postulated by de Groot\, van Leeuwen\, and van Weert (GLW). Using Bjorken symmetry we show how this formalism may be used to determine observables describing the pol arization of particles measured in the experiment.\n\nhttps://indico.bitp. kiev.ua/event/7/contributions/166/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/166/ END:VEVENT BEGIN:VEVENT SUMMARY:Formation of regular domain structures with small period in ferroe lectrics during phase transitions DTSTART;VALUE=DATE-TIME:20201223T082000Z DTEND;VALUE=DATE-TIME:20201223T084000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-204@indico.bitp.kiev.ua DESCRIPTION:Speakers: Olga Mazur (Institute for Physics of Mining Proceses of the NAS of Ukraine)\nRegular domain structures (RDS) with submicron pe riod are widely used in nonlinear optics\, non-volatile memory and laser i nvestigations\, which causes a significant interest in research to create the new methods for its fabrication. Classical methods of the RDSs formati on do not allow us to achieve the required high precision necessary for mo dern devices. Within the framework of the Landau – Ginzburg phenomenolog ical theory an innovative method for fabrication RDS with micron and submi cron period was proposed.\n Using the lithium tantalate crystal as an exa mple\, the kinetics of ordering of high non-equilibrium domain structure n ear Curie point under the influence of external high-frequency electric fi eld was investigated. It was shown that the quenching depth of the sample influences on the nature of the evolution of the system\, but not on its f inal result. Independently of the quenching depth\, the system evolves to a polydomain (regular) structure\, which remains stable even when the exte rnal electric field is turned off.\n There was shown that the effect of t he external high-frequency electric field on the relaxing domain structure has a threshold character depending on the frequency and the amplitude of the electric field. Critical values of these parameters for ferroelectric s that undergo the second order phase transition can be observed from the model. For lithium tantalate crystal the critical frequency is $f_{cr}$ = 4.8∙1010 Hz and the critical amplitude is $E_{cr}$ = 1.26∙106 V/m (Fig . 1). The RDS formation takes place in cases\, when $f > f_{cr}$ or $E 3K )$ the critical value of the amplitude is determined only by the frequency of the external electric field (Table 1).\n\nFig 1. Phase trajectories of the system for the parameters $r_c(0)=2$\, $\\overline{\\pi}_0=0$\, $D_0= 0.001$\, $f=10^{10}$ Hz\, $\\alpha=0.03$. Curves 1-4 correspond to the amp litudes of electric field $|\\varepsilon_m|$: {0.01\; 0.031\; 0.0315\; 0.0 5} respectively (in dimensionless units)\n\nTable 1. Critical values of th e amplitude of the external electric field $E_{cr}(10^5 V/m)$ depending on the frequency $\\Omega$ and quenching temperature $T_1$\n\nThere was show n that the evolution of domains can occurs with the formation of short-liv ed quasistationary asymmetric polydomain phases\, which can exist up to se veral minutes (Fig. 1). The developed model is not only applied\, but also fundamental. The relaxation process is accompanied by a gradual enlargeme nt of the domain structure\, which obeys the square root law. The derived time dependence of the correlation radius makes it possible to estimate th e degree of enlargement of the domain structure and determine the fundamen tal parameter — the radius of interatomic interaction. Due to the format ion of domains immediately after rapid quenching this method allows the us e of electric fields of small amplitude. A similar effect allows us to dir ect the process of ordering the system to the formation of domains of the desired type. It is expected that this approach will reduce the risk of cr ystal destruction and significantly increase the precision of the RDS obta ined.\n\nhttps://indico.bitp.kiev.ua/event/7/contributions/204/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/204/ END:VEVENT BEGIN:VEVENT SUMMARY:Properties of star-forming galaxies: applications for cosmology DTSTART;VALUE=DATE-TIME:20201222T071500Z DTEND;VALUE=DATE-TIME:20201222T080000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-210@indico.bitp.kiev.ua DESCRIPTION:Speakers: Yuriy Izotov (Bogolyubov Institute for Theoretical P hysics of the National Academy of Sciences of Ukraine)\nThe properties of nearby compact star-forming galaxies determined from recent studies are di scussed. These galaxies are very similar to the galaxies in the early Univ erse and can be considered as building blocks for formation of giant galax ies. The important features of compact star-forming galaxies are low masse s\, low content of elements heavier than helium\, and a very high star-for ming activity. These properties make compact star-forming galaxies suitabl e for solving several cosmological problems. First of them is the search f or and the detailed study of the galaxies with extremely low content of el ements heavier than helium. Such galaxies are the best proxies of the earl ist galaxies formed in the Universe. The second problem is related to the primordial nucleosynthesis\, which is happened when the age of the Univers e was only 2-3 minutes. Finally\, the third discussed problem is the reion ization of the Universe\, which happened when its age was 200 - 1000 milli on years. For a reference\, the age of the Universe now is 13.7 billion ye ars.\n\nhttps://indico.bitp.kiev.ua/event/7/contributions/210/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/210/ END:VEVENT BEGIN:VEVENT SUMMARY:Triple Supermassive Black Hole evolution in NGC 6240 DTSTART;VALUE=DATE-TIME:20201222T105000Z DTEND;VALUE=DATE-TIME:20201222T111000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-164@indico.bitp.kiev.ua DESCRIPTION:Speakers: Margaryta Sobolenko (Main Astronomical Observatory N AS of Ukraine)\nOne of the main possible ways to create the supermassive b lack hole (SMBH) is a so-called hierarchical merging scenario. At the fina l phase of interacting and colliding host galaxies\, the central SMBHs are observed as SMBH binary (SMBHB) candidates at different separations from hundreds of pc to mpc. But only several triple SMBHs systems have been det ected so far.\nOne of them is a well studied ULIRG galaxy NGC 6240 which w as first spatially and spectroscopically resolved in X-rays by Chandra as SMBHB system. Later high-resolution data from MUSE instrument at the ESO V LT may resolve the third active galactic nuclei (AGN). Dynamical calculati on of the central SMBH triple merging in a dense stellar environment allow s us to retrace their evolution from kpc to mpc scales. \nWe present the s et of direct N-body simulations with different particle numbers (N=67.5k\, 135k\, 240k\, 540k) and five different randomizations of initial position s and velocities of particles. \nWe found the formation of hierarchical tr iple systems in approximately 80 per cent of systems\, while other 20 per cent of systems fly apart. In large part of the formed hierarchical tripl e systems\, we observe the oscillation of eccentricities and inclination b etween inner and outer orbits\, which is the demonstration of Lidov-Kozai mechanism. This process can be one more mechanism to solve the merging BHs “last final parsec” problem.\nFurther detailed research of rare dual/ multiple BHs in a dense stellar environment (based on observations data) c an clarify the dynamical co-evolution of central BHs and their host-galaxi es.\n\nhttps://indico.bitp.kiev.ua/event/7/contributions/164/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/164/ END:VEVENT BEGIN:VEVENT SUMMARY:Partitioning electrostatic molecular properties into the localized contributions DTSTART;VALUE=DATE-TIME:20201223T130500Z DTEND;VALUE=DATE-TIME:20201223T132500Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-183@indico.bitp.kiev.ua DESCRIPTION:Speakers: Tymofii Nikolaienko (Taras Shevchenko National Unive rsity of Kyiv)\nApproximations for the molecular dipole moment vector as w ell as for the spatial distributions of the charge density and electrostat ic potential in terms of localized contributions associated with individua l atoms and covalent bonds are discussed. The application of recently prop osed CLPO method [1] yielding the chemically meaningful set of localized o rbitals particularly suitable for this application is considered. The role of the atomic lone electron pairs and bonding orbitals charge densities i s highlighted in achieving an accurate decomposition of electrostatic mole cular properties into the localized contributions. Comparison with simple point-charge methods\, traditionally used in force fields for molecular dy namics simulations\, is made. Impact of accuracy of the considered decompo sitions on electrostatic component of intermolecular interaction energy is quantified for the standard test set of non-covalently bounded complexes GMTKN55 [3].\n*Acknowledgements.* The work has been partially supported by the National Research Foundation of Ukraine (project No. 101/01.2020).\n\ n\n[1] T. Y. Nikolaienko and L. A. Bulavin\, *Int. J. Quantum Chem.* (2019 )\, **119**: e25798.\n[2] L.Goerigk\, A.Hansen\, C.Bauer\, S.Ehrlich\, A.N ajibi and S.Grimme\, *Phys.Chem.Chem.Phys.* (2017)\, **19**:32184.\n\nhttp s://indico.bitp.kiev.ua/event/7/contributions/183/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/183/ END:VEVENT BEGIN:VEVENT SUMMARY:Low-frequency modes of water vibrations in the minor groove of DNA double helix DTSTART;VALUE=DATE-TIME:20201223T141000Z DTEND;VALUE=DATE-TIME:20201223T143000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-198@indico.bitp.kiev.ua DESCRIPTION:Speakers: Tatyana Bubon ( Bogolyubov Institute for Theoretical Physics )\nWater and ions around DNA macromolecule are paramount for the stability of the double helix structure and found to mediate the vital bio logical process such as nucleic-protein recognition\, and the interaction with the biologically active compounds. DNA interacts strongly with surrou nding water molecules and counterions making the hydration shell with diff erent structural and dynamical features in different regions of the double helix (minor and major grooves\, phosphate groups). In the DNA minor groo ve water molecules are highly ordered and in the case of AATT nucleotide s equence\, the spine of hydration is formed [1]. In the present research [ 2]\, the vibrations of hydration spine have been studied to establish the mode of translational vibrations of water molecules in the DNA low-frequen cy spectra ($\n\nhttps://indico.bitp.kiev.ua/event/7/contributions/198/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/198/ END:VEVENT BEGIN:VEVENT SUMMARY:Potential electron scattering by the threonine andtyrosine amino a cid biomolecules DTSTART;VALUE=DATE-TIME:20201223T143000Z DTEND;VALUE=DATE-TIME:20201223T145000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-215@indico.bitp.kiev.ua DESCRIPTION:Speakers: Oleksandr Vasyliev (Institute of Electron Physics)\n Our report is devoted to a brief exposition of methodics of the descriptio n of potential electron scattering on complex molecules. In the Additivity Rule approach the differential and integral cross-sections of elastic ele ctron scattering by amino acids biomolecules\, threonine and tyrosine are calculated.\nExpressions for amplitudes and cross sections of electron sca ttering on molecules in the independent atoms model were given. The Additi vity Rule approach was described. Expressions for amplitudes and different ial cross sections of electron scattering on the atoms of which the molecu le consists were given. The scattering phase shifts are calculated in the optical potential method of the ELSEPA program.\nTheoretical calculations of differential cross sections of electron scattering on biomolecules (Thr eonine and Tyrosine) were made with energy levels of 20\, 40\, 60\, 75\, 1 00\, 150 eV. Theoretical calculations of integral cross sections of electr on scattering on same biomolecules were made as well. From the obtained re sults\, we saw that behaviour of differential cross sections of electron s cattering is pretty smooth and is characterized with wide graph minimum. T his minimum gets wider with the increase of collision energy.\n\nhttps://i ndico.bitp.kiev.ua/event/7/contributions/215/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/215/ END:VEVENT BEGIN:VEVENT SUMMARY:Dualities in QCD phase diagram DTSTART;VALUE=DATE-TIME:20201222T125000Z DTEND;VALUE=DATE-TIME:20201222T131000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-180@indico.bitp.kiev.ua DESCRIPTION:Speakers: Roman Zhokhov (IZMIRAN\, Troitsk\, Moscow\; IHEP\, P rotvino)\nThe talk is devoted to QCD phase diagram studies\, including the region of large baryon density that will be probed at NICA.\nRecently it has been shown that in the large-Nc limit (Nc is the number of colors of q uarks) there exist duality correspondences (symmetries) in the phase portr ait\, which are the symmetries of the thermodynamic potential and the phas e structure itself. The first one is a duality between the chiral symmetry breaking and the charged pion condensation phenomena. And there are two o ther dualities that hold only for chiral symmetry breaking and charged pio n condensation phenomena separately. For example\, we have shown that char ged pion condensation does not feel the difference between chiral and isos pin imbalances of the medium. They were shown to exist in the matter with chiral imbalance that can be produced in compact stars or heavy ion collis ions. One of the key conclusions of these studies is the fact that chiral imbalance generates charged pion condensation in dense baryonic/quark matt er. It was shown that our results in particular cases are consistent with the simulation of lattice QCD\, which is possible in these cases.\nDuality was used to show that there takes place catalysis of chiral symmetry brea king by chiral imbalance.\nIt was also shown that chiral imbalance generat es the phenomenon of charged pion condensation in dense baryonic/quark mat ter even in the case of charge neutral matter\, which is interesting in th e context of the astrophysics of neutron stars.\nIt is known that chiral i mbalance can occur in high energy experiments of the collision of heavy io ns\, due to temperature and sphaleron transitions. Our studies show that d ifferent types of chiral imbalance can occur in the cores of neutron stars or in heavy ion experiments\, where large baryon densities can be reached \, due to another phenomena - the so-called chiral separation and chiral v ortical effects.\nDuality was shown to exist even in case of inhomogeneous condensates. This example shows that the duality is not just entertaining mathematical property but an instrument with very high predictivity power .\nThe unified picture and full phase diagram of isospin imbalanced dense quark matter have been assembled. Acting on this diagram by a dual transfo rmation\, we obtained\, in the framework of an approach with spatially inh omogeneous condensates and without any calculations\, a full phase diagram of chirally asymmetric dense medium.\nContinuing our studies of dualities \, we noted that there are dualities in 2-color QCD that are connected wit h adiitional symmetry of QCD with two colors namely Pauli-Gursey symmetry. \nIt has been also shown that found duality is a more fundamental and can be shown at the level of Lagrangian. It has been shown that duality is a p roperty of real QCD. It is not bounded by large Nc approximation and exist s in the cases of 2 and 3 and infinite number of colours.\n\nReferences:\n Phys.Rev. D95 (2017) no.10\, 105010\nPhys.Rev. D97 (2018) no.5\, 054036\nP hys.Rev. D98 (2018) no.5\, 054030\nEur.Phys.J. C79 (2019) no.2\, 151\nJHEP 1906 (2019) 006\nPhys. Rev. D 100\, 034009 (2019)\nJHEP 06 (2020) 148\nEu r.Phys.J.C 80 (2020) 10\, 995\n\nhttps://indico.bitp.kiev.ua/event/7/contr ibutions/180/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/180/ END:VEVENT BEGIN:VEVENT SUMMARY:Collective oscillations of plasma and order parameter in graphene counterflow superconductors. DTSTART;VALUE=DATE-TIME:20201223T080000Z DTEND;VALUE=DATE-TIME:20201223T082000Z DTSTAMP;VALUE=DATE-TIME:20260419T013522Z UID:indico-contribution-7-202@indico.bitp.kiev.ua DESCRIPTION:Speakers: Kostiantyn Hermash (Institute for Single Crystals of NAS of Ukraine)\nIt is known [1] that in systems with Cooper pairing a sp ecific collective excitations can exist\, such as: the Anderson–Bogoliub ov mode (oscillations of the phase of the order parameter)\, the Schmid mo de (oscillations of the modulus of the order parameter)\, and the Carlson –Goldman mode (coupled oscillations of the phase of the order parameter and the scalar potential). These modes can exist under certain conditions. A genuine Anderson–Bogoliubov mode can appear in neutral superfluids\, and the Carlson–Goldman mode exists in a very narrow temperature range n ear $T_c$.\nWe consider [4] a possibility of these modes existence in a do uble layer graphene system with electron-hole pairing. Such a system consi sts of two parallel graphene layers\, which are spatially separated. If on e layer has an electron conductivity and the other layer has a hole conduc tivity\, then electrons and holes from the opposite layers can form pairs\ , which are similar to the Cooper pairs. This system is an example of a so -called counterflow superconductor [2\,3].\nThe influence of electron-hole pairing in the double layer graphene system on collective plasma excitati ons is investigated under accounting for the order parameter fluctuations. It is established that out-of-phase oscillations of the order parameters of two spin subsystems are uncoupled from electromagnetic field oscillatio ns. The spectrum of these oscillations splits into two branches: a low-ene rgy (weakly damped\, $\\hbar\\omega 2\\Delta$) ones. Here $2\\Delta$ is t he gap in the electron spectrum caused by the pairing. The low-energy bran ch can be considered as an analog of Anderson–Bogoliubov mode and the hi gh-energy—as an analog of Schmid mode. At small wave vectors $q$ the And erson–Bogoliubov mode has an acoustic dispersion $\\omega \\approx q v_{ F} / \\sqrt{2}$ ($v_{F}$ is the Fermi velocity)\, and its frequency satura tes at $\\hbar \\omega = 2\\Delta$ at large $q$. The Schmid mode exists on ly at small $q$.\nIt is shown that in-phase oscillations of the order para meters of two spin subsystems are hybridized with out-of-phase oscillation s of scalar potentials in layers. The spectrum of these oscillations also splits into two branches: a low-energy (weakly damped\, $\\hbar\\omega 2\ \Delta$). The low-energy mode can be interpreted as Carlson–Goldman mode and the high-energy—as a strongly damped acoustic plasmon mode. The Car lson–Goldman mode exists at all temperatures below the critical one\, in contrast with conventional superconductors in which this mode appears onl y near the critical temperature. Similarly to the Anderson–Bogoliubov mo de\, the Carlson–Goldman mode demonstrates an acoustic dispersion at sma ll $q$ and its frequency saturates at $\\hbar \\omega = 2\\Delta$ at large $q$.\nIt is established [4\,5] the existence of two symmetric (optical) p lasmon modes in counterflow superconductors\, which correspond to in-phase oscillations of the scalar potentials in the layers. These modes are unco upled from order parameter oscillations.\n\n[1] I. O. Kulik\, Ora Entin-Wo hlman\, and R. Orbach\, J. Low Temp. Phys. 43\, 591 (1981).\n[2] S. I. She vchenko\, Sov. J. Low Temp. Phys. 2\, 251 (1976).\n[3] D. V. Fil and S. I. Shevchenko\, LTP 44\, 867 (2018).\n[4] K. V. Germash and D. V. Fil\, Phys . Rev. B 99\, 125412 (2019).\n[5] K. V. Germash and D. V. Fil\, Phys. Rev. B 93\, 205436 (2016).\n\nhttps://indico.bitp.kiev.ua/event/7/contribution s/202/ LOCATION:Online meeting URL:https://indico.bitp.kiev.ua/event/7/contributions/202/ END:VEVENT END:VCALENDAR