Selected Papers from “Theory of Hadronic Matter under Extreme Conditions”

A special issue of Particles (ISSN 2571-712X).

Deadline for manuscript submissions: closed (30 April 2020) | Viewed by 27544

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1. Institute of Theoretical Physics, University of Wroclaw, 50-204 Wroclaw, Poland
2. Center for Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany
3. Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-1328 Dresden, Germany
Interests: quantum field theory; quantum statistics; quark gluon plasma; heavy ion collisions; compact stars
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1. Institute for Theoretical and Experimental Physics, NRC ”Kurchatov Institute”, 117218 Moscow, Russia
2. Far Eastern Federal University, School of Biomedicine, 690950 Vladivostok, Russia
3. Bogoliubov Laboratory of Theoretical Physics, JINR, 141980 Dubna, Russia4. Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia

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1. Matej Bel University, SK-97401 Banska Bystrica, Slovakia
2. Laboratory of Theoretical Physics, 1Joint Institute for Nuclear Research, RU-141980 Dubna, Russia
Interests: hadron structure; hadron resonances; particle production in heavy-ion collisions; in-medium effects; nuclear equation of state; neutron star physics
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Bogoliubov Laboratory of Theoretical Physics, JINR, 141980 Dubna, Russia

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Special Issue Information

Dear colleagues,

We are happy to announce that Particles and the organizers of the conference "The II International Workshop on Theory of Hadronic Matter under Extreme Conditions" will collaborate to produce a Special Issue volume, for extended versions of selected papers from this conference (https://indico.jinr.ru/event/834/overview).

In its nature, theoretical investigations in the field of relativistic heavy-ion collisions have a multidisciplinary character involving physics at various energy scales. They ask not only for a resolution of the number of fundamental problems but also phenomenological studies directly connected with experiments. The progress in this field relies on a coherent implementation of a wide range of methods of quantum chromodynamics, relativistic nuclear physics, kinetic theory, hydrodynamics and physics of critical phenomena in finite short-lived systems. The construction of the Nuclotron-based Ion Collider fAcility (NICA), based on superconducting rings for performing experiments with heavy-ion beams in the collider as well as the fixed target mode sets up an auspicious environment for enhancement of theoretical physics activities at the Joint Institute for Nuclear Research (JINR) related to relativistic heavy ion physics.

As the Guest Editors, we would like to invite you to submit your unpublished and original research relevant to this topic for publication in this special volume of Particles. All submissions will be peer reviewed by internationally recognized experts. The Article Processing Charge (APC) for submissions from the conference will be free of charge.

Prof. Dr. David Blaschke
Dr. Victor Braguta
Prof. Evgeni Kolomeitsev
Dr. Sergei N. Nedelko
Dr. Alexandra Friesen
Dr. Vladimir E. Voronin
Guest Editors

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Keywords

  • Confinement & chiral symmetry breaking in QCD
  • Hadronic matter at nonzero temperature and baryon density
  • QCD phase diagram
  • Hydrodynamic and kinetic approaches to dense matter
  • Approach to equilibrium
  • Critical phenomena in finite statistical systems
  • Strong electromagnetic fields in relativistic heavy ion collisions
  • Lattice QCD
  • Functional continuum methods
  • Models of confinement and hadronization in QCD

Published Papers (12 papers)

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12 pages, 363 KiB  
Article
Gluon Propagators in QC2D at High Baryon Density
by Vitaly Bornyakov, Andrey Kotov, Aleksandr Nikolaev and Roman Rogalyov
Particles 2020, 3(2), 308-319; https://doi.org/10.3390/particles3020023 - 1 Apr 2020
Cited by 5 | Viewed by 2604
Abstract
We study the transverse and longitudinal gluon propagators in the Landau-gauge lattice QCD with gauge group S U ( 2 ) at nonzero quark chemical potential and zero temperature. We show that both propagators demonstrate substantial dependence on the quark chemical potential. This [...] Read more.
We study the transverse and longitudinal gluon propagators in the Landau-gauge lattice QCD with gauge group S U ( 2 ) at nonzero quark chemical potential and zero temperature. We show that both propagators demonstrate substantial dependence on the quark chemical potential. This observation does not agree with earlier findings by other groups. Full article
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6 pages, 1407 KiB  
Article
Properties and Composition of Magnetized Nuclei
by V.N. Kondratyev
Particles 2020, 3(2), 272-277; https://doi.org/10.3390/particles3020021 - 1 Apr 2020
Cited by 2 | Viewed by 1750
Abstract
The properties and mass distribution of the ultramagnetized atomic nuclei which arise in heavy-ion collisions and magnetar crusts, during Type II supernova explosions and neutron star mergers are analyzed. For the magnetic field strength range of 0.1–10 teratesla, the Zeeman effect leads [...] Read more.
The properties and mass distribution of the ultramagnetized atomic nuclei which arise in heavy-ion collisions and magnetar crusts, during Type II supernova explosions and neutron star mergers are analyzed. For the magnetic field strength range of 0.1–10 teratesla, the Zeeman effect leads to a linear nuclear magnetic response that can be described in terms of magnetic susceptibility. Binding energies increase for open shell and decrease for closed shell nuclei. A noticeable enhancement in theyield of corresponding explosive nucleosynthesis products with antimagic numbers is predicted for iron group and r-process nuclei. Magnetic enrichment in a sampleof 44Ti corroborate theobservational results and imply a significant increase in the quantity of the main titanium isotope, 48Ti, in the chemical composition of galaxies. The enhancement of small mass number nuclides in the r-process peak may be due to magnetic effects. Full article
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15 pages, 1557 KiB  
Article
Exploring the Partonic Phase at Finite Chemical Potential in and out-of Equilibrium
by O. Soloveva, P. Moreau, L. Oliva, V. Voronyuk, V. Kireyeu, T. Song and E. Bratkovskaya
Particles 2020, 3(1), 178-192; https://doi.org/10.3390/particles3010015 - 2 Mar 2020
Cited by 8 | Viewed by 2372
Abstract
We study the influence of the baryon chemical potential μ B on the properties of the Quark–Gluon–Plasma (QGP) in and out-of equilibrium. The description of the QGP in equilibrium is based on the effective propagators and couplings from the Dynamical QuasiParticle Model (DQPM) [...] Read more.
We study the influence of the baryon chemical potential μ B on the properties of the Quark–Gluon–Plasma (QGP) in and out-of equilibrium. The description of the QGP in equilibrium is based on the effective propagators and couplings from the Dynamical QuasiParticle Model (DQPM) that is matched to reproduce the equation-of-state of the partonic system above the deconfinement temperature T c from lattice Quantum Chromodynamics (QCD). We study the transport coefficients such as the ratio of shear viscosity η and bulk viscosity ζ over entropy density s, i.e., η / s and ζ / s in the ( T , μ ) plane and compare to other model results available at μ B = 0 . The out-of equilibrium study of the QGP is performed within the Parton–Hadron–String Dynamics (PHSD) transport approach extended in the partonic sector by explicitly calculating the total and differential partonic scattering cross sections based on the DQPM and the evaluated at actual temperature T and baryon chemical potential μ B in each individual space-time cell where partonic scattering takes place. The traces of their μ B dependences are investigated in different observables for symmetric Au + Au and asymmetric Cu + Au collisions such as rapidity and m T -distributions and directed and elliptic flow coefficients v 1 , v 2 in the energy range 7.7 GeV s N N 200 GeV. Full article
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9 pages, 1036 KiB  
Article
Using the Beth–Uhlenbeck Approach to Describe the Kaon to Pion Ratio in a 2 + 1 Flavor PNJL Model
by David Blaschke, Alexandra Friesen, Yuri Kalinovsky and Andrey Radzhabov
Particles 2020, 3(1), 169-177; https://doi.org/10.3390/particles3010014 - 2 Mar 2020
Cited by 3 | Viewed by 1903
Abstract
The kaon to pion ratios are discussed in the framework of a 2 + 1 flavor PNJL model. In order to interpret the behavior of bound states in medium, the Beth–Uhlenbeck approach is used. It is shown that, in terms of phase shifts [...] Read more.
The kaon to pion ratios are discussed in the framework of a 2 + 1 flavor PNJL model. In order to interpret the behavior of bound states in medium, the Beth–Uhlenbeck approach is used. It is shown that, in terms of phase shifts in the K + channel, an additional low-energy mode could appear as a bound state in medium, since the masses of the quark constituents are different. The comparison with experimental data for the ratios is performed and the influence of the anomalous mode to the “horn” effect in the K + / π + ratio is discussed. Full article
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9 pages, 312 KiB  
Article
Particle Production in XeXe Collisions at the LHC within the Integrated Hydrokinetic Model
by Yuri Sinyukov, Musfer Adzhymambetov and Volodymyr Shapoval
Particles 2020, 3(1), 114-122; https://doi.org/10.3390/particles3010010 - 18 Feb 2020
Cited by 3 | Viewed by 2223
Abstract
The paper is devoted to the theoretical study of particle production in the Large Hadron Collider (LHC) Xe+Xe collisions at the energy s N N = 5 . 44 TeV. The description of common bulk observables, such as mean charged particle multiplicity, particle [...] Read more.
The paper is devoted to the theoretical study of particle production in the Large Hadron Collider (LHC) Xe+Xe collisions at the energy s N N = 5 . 44 TeV. The description of common bulk observables, such as mean charged particle multiplicity, particle number ratios, and p T spectra, is obtained within the integrated hydrokinetic model, and the simulation results are compared to the corresponding experimental points. The comparison shows that the model is able to adequately describe the measured data for the considered collision type, similarly as for the cases of Pb+Pb LHC collisions and top Relativistic Heavy Ion Collider (RHIC) energy Au+Au collisions, analyzed in our previous works. Full article
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12 pages, 468 KiB  
Article
New Canonical and Grand Canonical Density of States Techniques for Finite Density Lattice QCD
by Christof Gattringer, Michael Mandl and Pascal Törek
Particles 2020, 3(1), 87-98; https://doi.org/10.3390/particles3010008 - 10 Feb 2020
Cited by 5 | Viewed by 1763
Abstract
We discuss two new density of states approaches for finite density lattice QCD (Quantum Chromo Dynamics). The paper extends a recent presentation of the new techniques based on Wilson fermions, while here, we now discuss and test the case of finite density QCD [...] Read more.
We discuss two new density of states approaches for finite density lattice QCD (Quantum Chromo Dynamics). The paper extends a recent presentation of the new techniques based on Wilson fermions, while here, we now discuss and test the case of finite density QCD with staggered fermions. The first of our two approaches is based on the canonical formulation where observables at a fixed net quark number N are obtained as Fourier moments of the vacuum expectation values at imaginary chemical potential θ . We treat the latter as densities that can be computed with the recently developed functional fit approach. The second method is based on a direct grand canonical evaluation after rewriting the QCD partition sum in terms of a suitable pseudo-fermion representation. In this form, the imaginary part of the pseudo-fermion action can be identified and the corresponding density may again be computed with the functional fit approach. We develop the details of the two approaches and discuss some exploratory first tests for the case of free fermions where reference results for assessing the new techniques may be obtained from Fourier transformation. Full article
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7 pages, 1173 KiB  
Article
The Dirac Spectrum and the BEC-BCS Crossover in QCD at Nonzero Isospin Asymmetry
by Bastian B. Brandt, Francesca Cuteri, Gergely Endrődi and Sebastian Schmalzbauer
Particles 2020, 3(1), 80-86; https://doi.org/10.3390/particles3010007 - 4 Feb 2020
Cited by 11 | Viewed by 2099
Abstract
For large isospin asymmetries, perturbation theory predicts the quantum chromodynamic (QCD) ground state to be a superfluid phase of u and d ¯ Cooper pairs. This phase, which is denoted as the Bardeen-Cooper-Schrieffer (BCS) phase, is expected to be smoothly connected to the [...] Read more.
For large isospin asymmetries, perturbation theory predicts the quantum chromodynamic (QCD) ground state to be a superfluid phase of u and d ¯ Cooper pairs. This phase, which is denoted as the Bardeen-Cooper-Schrieffer (BCS) phase, is expected to be smoothly connected to the standard phase with Bose-Einstein condensation (BEC) of charged pions at μ I m π / 2 by an analytic crossover. A first hint for the existence of the BCS phase, which is likely characterised by the presence of both deconfinement and charged pion condensation, comes from the lattice observation that the deconfinement crossover smoothly penetrates into the BEC phase. To further scrutinize the existence of the BCS phase, in this article we investigate the complex spectrum of the massive Dirac operator in 2+1-flavor QCD at nonzero temperature and isospin chemical potential. The spectral density near the origin is related to the BCS gap via a generalization of the Banks-Casher relation to the case of complex Dirac eigenvalues (derived for the zero-temperature, high-density limits of QCD at nonzero isospin chemical potential). Full article
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18 pages, 399 KiB  
Article
Dense Baryonic Matter and Applications of QCD Phase Diagram Dualities
by Tamaz G. Khunjua, Konstantin G. Klimenko and Roman N. Zhokhov
Particles 2020, 3(1), 62-79; https://doi.org/10.3390/particles3010006 - 19 Jan 2020
Cited by 8 | Viewed by 2584
Abstract
Recently it has been found that quantum chromodynamics (QCD) phase diagram possesses a duality between chiral symmetry breaking and pion condensation. For the first time this was revealed in the QCD motivated toy model. Then it was demonstrated in effective models as well [...] Read more.
Recently it has been found that quantum chromodynamics (QCD) phase diagram possesses a duality between chiral symmetry breaking and pion condensation. For the first time this was revealed in the QCD motivated toy model. Then it was demonstrated in effective models as well and new additional dualities being found. We briefly recap the main features of this story and then discuss its applications as a tool to explore the QCD phase structure. The most appealing application is the possibility of getting the results on the QCD phase diagram at large baryon density. Taking the idea from large 1 / N c universalities it was argued that the scenario of circumventing the sign problem with the help of dualities seems plausible. It is also discussed that there is a persistent problem about whether there should be catalysis or anti-catalysis of chiral symmetry breaking by chiral imbalance. One can probably say that the issue is settled after lattice results (first principle approach), where the catalysis was observed. But they used an unphysically large pion mass so it is still interesting to get additional indications that this is the case. It is shown just by the duality property that there exists catalysis of chiral symmetry breaking. So, having in mind our results and the earlier lattice simulations, one can probably claim that this issue is settled. It is demonstrated that the duality can be used to obtain new results. As an example, it is showcased how the phase structure of dense quark matter with chiral imbalance (with possibility of inhomogeneous phases) can be obtained from the knowledge of a QCD phase diagram with isopin asymmetry. Full article
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15 pages, 448 KiB  
Article
Color Transparency and Hadron Formation Effects in High-Energy Reactions on Nuclei
by Alexei Larionov and Mark Strikman
Particles 2020, 3(1), 24-38; https://doi.org/10.3390/particles3010004 - 17 Jan 2020
Cited by 3 | Viewed by 2047
Abstract
An incoming or outgoing hadron in a hard collision with large momentum transfer gets squeezed in the transverse direction to its momentum. In the case of nuclear targets, this leads to the reduced interaction of such hadrons with surrounding nucleons which is known [...] Read more.
An incoming or outgoing hadron in a hard collision with large momentum transfer gets squeezed in the transverse direction to its momentum. In the case of nuclear targets, this leads to the reduced interaction of such hadrons with surrounding nucleons which is known as color transparency (CT). The identification of CT in exclusive processes on nuclear targets is of significant interest not only by itself but also due to the fact that CT is a necessary condition for the applicability of factorization for the description of the corresponding elementary process. In this paper we discuss the semiexclusive processes A ( e , e π + ) , A ( π , l l + ) and A ( γ , π p ) . Since CT is closely related to hadron formation mechanism, the reduced interaction of ’pre-hadrons’ with nucleons is a common feature of generic high-energy inclusive processes on nuclear targets, such as hadron attenuation in deep inelastic scattering (DIS). We will discuss the novel way to study hadron formation via slow neutron production induced by a hard photon interaction with a nucleus. Finally, the opportunity to study hadron formation effects in heavy-ion collisions in the NICA regime will be considered. Full article
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8 pages, 236 KiB  
Article
Chiral Perturbation Theory vs. Linear Sigma Model in a Chiral Imbalance Medium
by Alexander Andrianov, Vladimir Andrianov and Domenec Espriu
Particles 2020, 3(1), 15-22; https://doi.org/10.3390/particles3010002 - 8 Jan 2020
Cited by 7 | Viewed by 2201
Abstract
We compare the chiral perturbation theory (ChPT) and the linear sigma model (LSM) as realizations of low energy quantum chromodynamics (QCD) for light mesons in a chirally-imbalanced medium. The relations between the low-energy constants of the chiral Lagrangian and the corresponding constants of [...] Read more.
We compare the chiral perturbation theory (ChPT) and the linear sigma model (LSM) as realizations of low energy quantum chromodynamics (QCD) for light mesons in a chirally-imbalanced medium. The relations between the low-energy constants of the chiral Lagrangian and the corresponding constants of the linear sigma model are established as well as the expressions for the decay constant of π -meson in the medium and for the mass of the a 0 . In the large N c count taken from QCD the correspondence of ChPT and LSM is remarkably good and provides a solid ground for the search of chiral imbalance manifestations in pion physics. A possible experimental detection of chiral imbalance (and therefore a phase with local parity breaking) is outlined in the charged pion decays inside the fireball. Full article
8 pages, 899 KiB  
Article
Improving Center Vortex Detection by Usage of Center Regions as Guidance for the Direct Maximal Center Gauge
by Rudolf Golubich and Manfried Faber
Particles 2019, 2(4), 491-498; https://doi.org/10.3390/particles2040030 - 11 Dec 2019
Cited by 6 | Viewed by 2531
Abstract
The center vortex model of quantum chromodynamic states that vortices, a closed color-magnetic flux, percolate the vacuum. Vortices are seen as the relevant excitations of the vacuum, causing confinement and dynamical chiral symmetry breaking. In an appropriate gauge, as direct maximal center gauge [...] Read more.
The center vortex model of quantum chromodynamic states that vortices, a closed color-magnetic flux, percolate the vacuum. Vortices are seen as the relevant excitations of the vacuum, causing confinement and dynamical chiral symmetry breaking. In an appropriate gauge, as direct maximal center gauge, vortices are detected by projecting onto the center degrees of freedom. Such gauges suffer from Gribov copy problems: different local maxima of the corresponding gauge functional can result in different predictions of the string tension. By using nontrivial center regions—that is, regions whose boundary evaluates to a nontrivial center element—a resolution of this issue seems possible. We use such nontrivial center regions to guide simulated annealing procedures, preventing an underestimation of the string tension in order to resolve the Gribov copy problem. Full article
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10 pages, 381 KiB  
Conference Report
Critical Behavior of (2 + 1)-Dimensional QED: 1/N Expansion
by Anatoly V. Kotikov and Sofian Teber
Particles 2020, 3(2), 345-354; https://doi.org/10.3390/particles3020026 - 10 Apr 2020
Cited by 29 | Viewed by 2448
Abstract
We present recent results on dynamical chiral symmetry breaking in (2 + 1)-dimensional QED with N four-component fermions. The results of the 1 / N expansion in the leading and next-to-leading orders were found exactly in an arbitrary nonlocal gauge. [...] Read more.
We present recent results on dynamical chiral symmetry breaking in (2 + 1)-dimensional QED with N four-component fermions. The results of the 1 / N expansion in the leading and next-to-leading orders were found exactly in an arbitrary nonlocal gauge. Full article
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