arXiv subjects

Yu. L. Kalinovsky

Publications and source records attributed to Yu. L. Kalinovsky.

At least 19 recordsLinked to original sources

arXiv2023

Diquarks and $Λ^0/π^+$, $Ξ^-/π^+$ ratios in the framework of the EPNJL model

The applicability of the effective models to the description of baryons and the behaviour of ratios of strange baryons to pions is discussed. In the framework of the EPNJL model, the Bethe - Salpeter equation is used to find masses of baryons, which are considered as diquark-quark state. Baryon melting is discussed at a finite chemical potential and a flavor dependence of the hadronic deconfinement temperature is pointed. It is shown that the description of the diquark-quark state at finite chemical potential is limited due to the occurrence of the Bose condensate. This effect is strongly manifested in the description of light diquarks and baryons. Both $Λ^0/π^+$ and $Ξ^-/π^+$ ratios show a sharp behaviour as functions of $T/μ_B$ variable, where T and $μ_B$ are calculated along the melting lines.

hep-ph↗

arXiv2021

Mott dissociation and kaon to pion ratio in the EPNJL model

The behaviour of pseudoscalar mesons within the SU(3)PNJL-like models is considered for finite T and $μ_B$. We compare the pole approximation (Breit-Wigner) with the Beth-Uhlenbeck approach. We evaluate the $K/π$ ratios along the phase transition line in the T-$μ_B$ plane with constant and $T/μ_B$-dependent pion and strange quark chemical potentials. Using the model, we can show that the splitting of kaon and anti-kaon masses appears as a result of introduction of density and this explains the difference in the $K^+/π^+$ ratio and $K^-/π^-$ ratio at low $\sqrt{s_{NN}}$ and their tendency to the same value at high $\sqrt{s_{NN}}$. A sharp "horn" effect in the $K^+/π^+$ ratio is explained by the enhanced pion production which can be described by occurrence of a nonequilibrium pion chemical potential of the order of the pion mass. We elucidate that the horn effect is not related to the existence of a critical endpoint in the QCD phase diagram.

hep-ph↗

arXiv2020

Chiral phase transition and kaon-to-pion ratios in the entanglement SU(3) PNJL model

Within the three-flavor PNJL and EPNJL chiral quark models we have obtained pseudoscalar meson properties in quark matter at finite temperature $T$ and baryochemical potential $μ_B$. We compare the meson pole (Breit-Wigner) approximation with the Beth-Uhlenbeck (BU) approach that takes into account the continuum of quark-antiquark scattering states when determining the partial densities of pions and kaons. We evaluate the kaon-to-pion ratios along the (pseudo-)critical line in the $T-μ_B$ plane as a proxy for the chemical freezeout line, whereby the variable $x=T/μ_B$ is introduced that corresponds to the conserved entropy per baryon as initial condition for the heavy-ion collision experiments. We present a comparison with the experimental pattern of kaon-to-pion ratios within the BU approach and using $x$-dependent pion and strange quark potentials. A sharp "horn" effect in the energy dependence $K^+/π^+$ ratio is explained by the enhanced pion production at energies above $\sqrt{s_{NN}}=8$ GeV, when the system enters the regime of meson dominance. This effect is in line with the enhancement of low-momentum pion spectra that is discussed as a precursor of the pion Bose condensation and entails the occurrence of a nonequilibrium pion chemical potential of the order of the pion mass. We elucidate that the horn effect is not related to the existence of a critical endpoint in the QCD phase diagram.

hep-ph↗

arXiv2020

QCD Phase Diagram at NICA energies: $K^+/π^+$ horn effect and light clusters in THESEUS

We discuss recent progress in the development of the three-fluid hydrodynamics-based program THESEUS towards an event generator suitable for applications to heavy-ion collisions at the intermediate energies of the planned NICA and FAIR experiments. We follow the strategy that modifications of particle distributions at the freeze-out surface in the QCD phase diagram may be mapped directly to the observable ones within a sudden freeze-out scheme. We report first results of these investigations for the production of light clusters (deuterons and tritons) which can be compared to experimental data from the HADES and the NA49 experiment and for the interpretation of the "horn" effect observed in the collision energy dependence of the $K^+/π^+$ ratio. Medium effects on light cluster production in the QCD phase diagram are negligible at the highest NICA energies but shall play a dominant role at the lowest energies. A sharp "horn"-type signal in the $K^+/π^+$ ratio can be obtained when the onset of Bose condensation modelled by a pion chemical potential results in an enhancement of pions at low momenta (which is seen at LHC energies) and would occur already in the NICA energy range.

hep-ph↗

arXiv2019

The role of the chiral phase transition in modelling the kaon to pion ratio

A sharp peak in the $K^+/π^+$ ratio in relativistic heavy-ion collision is discussed in the framework of the SU(3) Polyakov-loop extended NJL model with vector interaction. In the model, the $K^+/π^+$ ratio was calculated along the chiral phase transition line for different values of the vector coupling $g_V$. We showed that the value of the vector coupling had no significant effect on the $K^+/π^+$ behaviour.

nucl-th↗

arXiv2018

Strange matter and kaon to pion ratio in SU(3) PNJL model

The behavior of strange matter in the frame of the SU(3)Polyakov-loop extended Nambu-Jona-Lasinio model including $U_A(1)$ anomaly is considered. We discuss the appearance of a peak in the ratio of the number of strange mesons to non-strange mesons known as the "horn". The PNJL model gives a schematic description of the chiral phase transition and meson properties at finite temperature and density. Using the model, we can show that the splitting of kaon and anti-kaon masses appears as a result of introduction of density. This may explain the difference in the $K^+/π^+$ ratio and $K^-/π^-$ ratio at low $\sqrt{s_{NN}}$ and their tendency to the same value at high $\sqrt{s_{NN}}$. We also show that the rise in the ratio $K^+/π^+$ appears near CEP when we build the $K^+/π^+$ ratio along the phase transition diagram and it can be considered as a critical region signal.

hep-ph↗

arXiv2018

Decays of $τ\rightarrow ρ(770) (ρ'(1450)) ν_τ$ and $τ\rightarrow K^{}(892) (K^{'}(1410)) ν_τ$ in the extended Nambu - Jona- Lasinio model

In the extended Nambu - Jona - Lasinio model the decay widths $τ\rightarrow ρ(770) (ρ'(1450)) ν_τ$ and $τ\rightarrow K^{*}(892) (K^{*'}(1410)) ν_τ$ are studied in the quark one -loop approximation. Our estimations of the decay widths $τ\rightarrow K^{*}(892) (K^{*'}(1410)) ν_τ$ are in satisfactory agreement with experimantal data. In the paper, the decay widths $τ\rightarrow ρ(770) (ρ'(1450)) ν_τ$ are also calculated.

hep-ph↗

arXiv2014

Impact of the vector interaction on the phase structure of QCD matter

The 2-flavor Polyakov-loop extended model is generalized by taking into account the effective four-quark vector-type interaction with the coupling strengths, which are endowed with a dependence on the Polyakov field $Φ$. The effective vertex generates entanglement interaction between the Polyakov loop and the chiral condensate. We investigate the influence of an additional quark vector interaction and the entanglement interaction on the location of the critical end-point at the given chemical potential or quark density. It is shown that the finite value of the vector interaction strength $G_{\rm v}$ improves the model agreement with the lattice data. The influence of the non-zero $G_{\rm v}$ and entanglement on the thermodynamic observables and the curvature of the crossover boundary in the $T-μ$ plane is also examined.

hep-ph↗

arXiv2014

Pion dissociation and Levinson's theorem in hot PNJL quark matter

Pion dissociation by the Mott effect in quark plasma is described within the generalized Beth-Uhlenbeck approach on the basis of the PNJL model which allows for a unified description of bound, resonant and scattering states. As a first approximation, we utilize the Breit-Wigner ansatz for the spectral function and clarify its relation to the complex mass pole solution of the pion Bethe-Salpeter equation. Application of the Levinson theorem proves that describing the pion Mott dissociation solely by means of spectral broadening of the pion bound state beyond T_Mott leaves out a significant aspect. Thus we acknowledge the importance of the continuum of scattering states and show its role for the thermodynamics of pion dissociation.

nucl-th↗

arXiv2013

Pion and sigma meson dissociation in a modified NJL model at finite temperature

We investigate pion and sigma meson correlations in hot quark matter within a modified NJL model. Special emphasis is on the transformation of mesonic bound states to resonances (Mott dissociation) when due to the partial chiral symmetry restoration with increasing temperature the threshold of quark-antiquark continuum states drops below the meson mass at the corresponding Mott temperature. The description is based on evaluating the polarization functions for quark-antiquark (meson) correlations as a function of the temperature and the results can be represented by introducing modulus and phase of the complex propagator functions for the mesonic states. We study the effect of modelling confinement by introducing a low-momentum cutoff in loop integrals. We make the ansatz that this cutoff is identified with the dynamically generated quark mass gap and find an increase of the continuum threshold which makes the otherwise unbound sigma meson a bound state in the vacuum. We discuss the in-medium behavior of the mesonic phase shifts including the Mott effect and find accordance with the Levinson theorem.

hep-ph↗

arXiv2011

D mesons at finite temperature and density in the PNJL model

We study D meson resonances in hot, dense quark matter within the NJL model and its Polyakov-loop extension. We show that the mass splitting between D^+ and D^- mesons is moderate, not in excess of 100 MeV. When the decay channel into quasifree quarks opens (Mott effect) at densities above twice saturation density, the decay width reaches rapidly the value of 200 MeV which entails a spectral broadening sufficient to open J/psi dissociation processes. Contrary to results from hadronic mean-field theories, the chiral quark model does not support the scenario of a dropping D meson masses so that scenarios for J/psi dissociation by quark rearrangement built on the lowering of the threshold for this process in a hot and dense medium have to be reconsidered and should account for the spectral broadening.

hep-ph↗

arXiv2011

Decay of a scalar $σ$-meson near the critical end-point in the PNJL model

Properties of a scalar $σ$-meson are investigated in the two-flavor Nambu-Jona-Lasinio model with the Polyakov loop. Model analysis of the phase diagram of strong interacting matter is performed. The temperature dependence of the $σ\rightarrowππ$ decay width is studied at the zero chemical potential and near the critical end-point. The calculated strong coupling constant $g_{σππ}$ and the decay width are compared with available experimental data and other model results. Nonthermal enhancement of the total decay width is noted for the $σ$ meson near the critical end-point when the condition $m_σ\geq2m_π$ is broken.

nucl-th↗

arXiv2011

Thermodynamics in NJL-like models

Thermodynamic behavior of conventional Nambu-Jona-Lasinio and Polyakov-loop-extended Nambu-Jona-Lasinio models is compared. A particular attention is paid to the phase diagram in the ($T -μ$) plane.

hep-th↗

arXiv2009

Diquark Bose-Einstein condensation at strong coupling

We investigate the phase structure of the $SU_f(2)\otimes SU_c(3)$ Nambu--Jona-Lasinio model as a function of the scalar diquark coupling strength. Above a critical coupling, the binding energy is sufficiently large to overcompensate the quark masses and a massless scalar diquark bound state emerges which leads to Bose condensation already in the vacuum.

hep-ph↗

arXiv2009

Meson formfactor scheme for the chiral Lagrangian approach to J/psi breakup cross sections motivated by a relativistic quark model

We suggest a new scheme for the introduction of formfactors for the SU(4) chiral meson Lagrangian approach to the J/psi breakup cross sections by pion and rho meson impact. This mesonic formfactor scheme respects the fact that on the quark level of description the contact and the meson exchange diagrams are constructed by so-called box and triangle diagrams which contain a different number of vertex functions for the quark-meson coupling. We present a model calculation for Gaussian vertex functions within the meson formfactor scheme and compare the results with those of the usual global formfactor model. We calibrate the new meson formfactor model with results for the pion impact processes from a relativistic quark model calculation by Ivanov et al. and present predictions for the rho-meson induced processes. We provide a fit formula for the resulting energy-dependent cross sections.

hep-ph↗

arXiv2008

Two photon decays of scalar mesons in the quark NJL model

Two photon decays of scalar mesons f_0(980), a_0(980), σ(600) in the quark Nambu - Jona - Lasinio (NJL) model are calculated. The contributions of the meson loops are taken into account along with the quark loops (Hartree - Fock approximation). This corresponds to the next order of the 1/N_c expansion, where N_c=3 is the number of quark colors. It is shown that the meson and quark loops give comparable contributions to the amplitude. Moreover, in the process f_0(980)-> γγthe kaon loop plays the dominant role. A similar situation takes place in the decay ϕ-> f_0(980) γ\cite{physrev}. Our results are in satisfactory agreement with the recent experimental data.

hep-ph↗

arXiv2007

The QCD critical end point in the SU(3) Nambu--Jona-Lasinio model

We study the chiral phase transition at finite temperature $T$ and baryonic chemical potential $μ_B$ within the framework of the SU(3) Nambu-Jona-Lasinio (NJL) model. The QCD critical end point (CEP) and the critical line at finite $T$ and $μ_B$ are investigated: the study of physical quantities, such as the baryon number susceptibility and the specific heat in the vicinity the CEP, will provide relevant information concerning the order of the phase transition. The class of the CEP is determined by calculating the critical exponents of those quantities.

hep-ph↗

arXiv2007

Phase transitions in quark matter and behaviour of physical observables in the vicinity of the critical end point

We study the chiral phase transition at finite $T$ and $μ_B$ within the framework of the SU(3) Nambu-Jona-Lasinio (NJL) model. The QCD critical end point (CEP) and the critical line at finite temperature and baryonic chemical potential are investigated: the study of physical quantities, such as the baryon number susceptibility near the CEP, will provide complementary information concerning the order of the phase transition. We also analyze the information provided by the study of the critical exponents around the CEP.

hep-ph↗