NJL model with the modified quark-dependent coupling strength G

2017 ◽  
Vol 32 (20) ◽  
pp. 1750107 ◽  
Author(s):  
Zhou-You Fan ◽  
Wen-Kai Fan ◽  
Qing-Wu Wang ◽  
Hong-Shi Zong
Keyword(s):  
Coupling Strength ◽  
Finite Temperature ◽  
Chemical Potential ◽  
Chiral Limit ◽  
Pion Mass ◽  
Quark Condensate ◽  
Qcd Phase Diagram ◽  
Njl Model ◽  
Lattice Quantum ◽  
Current Quark

In this paper, the coupling strength G of the Nambu–Jona-Lasinio (NJL) model is modified by incorporating quark’s feedback into the gluon propagator. The modified two-flavor NJL model with the quark-dependent coupling strength is explored. The quark condensate in this framework has a conspicuous agreement with the lattice quantum chromodynamics (QCD) results at finite temperature. Then, it is compared with the original NJL model in both zero (chiral limit) and nonzero current quark mass. The QCD phase diagram and susceptibilities are investigated in the temperature–chemical potential [Formula: see text] plane. Therefore, the pseudo-critical temperature [Formula: see text] and the critical end point (CEP) are worked out and compared with original NJL model or lattice QCD results. In addition, the pion mass and decay constant are studied at finite temperature.

THE STUDY OF QCD PHASE TRANSITION AT FINITE TEMPERATURE AND CHIRAL CHEMICAL POTENTIAL IN A DYSON–SCHWINGER EQUATION MODEL

2013 ◽  
Vol 28 (23) ◽  
pp. 1350105 ◽  
Author(s):  
LIU-JUN LUO ◽  
SONG SHI ◽  
HONG-SHI ZONG
Keyword(s):  
Phase Transition ◽  
Finite Temperature ◽  
Chemical Potential ◽  
Chiral Limit ◽  
Quark Condensate ◽  
Equation Model ◽  
Qcd Phase Transition ◽  
Qcd Phase Diagram ◽  
Chiral Susceptibility ◽  
Current Quark

In this paper, we use a separable gluon propagator model to study the Quantum Chromodynamics (QCD) phase transition at finite temperature and chiral chemical potential. Using this model, we calculate the quark condensate and the chiral susceptibility at finite temperature and chiral chemical potential both in the chiral limit and at finite current quark mass. Based on these, we obtain the QCD phase diagram in the μ5-T plane.

Thermodynamic properties of light mesons and phase transition in an extended SU(2) NJL model

2019 ◽  
Vol 34 (13) ◽  
pp. 1950070
Author(s):  
J. R. Morones Ibarra ◽  
A. J. Garza Aguirre ◽  
Francisco V. Flores-Baez
Keyword(s):  
Chemical Potential ◽  
Pion Mass ◽  
Quark Condensate ◽  
The Other ◽  
Chiral Symmetry Restoration ◽  
Chiral Phase ◽  
Potential Dependence ◽  
Njl Model ◽  
The Masses ◽  
Sigma Meson

In this work, we study the temperature and chemical potential dependence of the masses of sigma and pion mesons as well as the quark condensate by using a SU(2) flavor version of the Nambu–Jona–Lassino model, introducing a prescription that mimics confinement. We have found that as the temperature increases, the mass of sigma shifts down, while the pion mass remains almost constant. On the other hand, the quark condensate decreases as the temperature and chemical potential increases. We have also analyzed the temperature and chemical potential dependence of the spectral function of the sigma meson, from which we observe at low values of T and [Formula: see text] an absence of a peak. Furthermore, as the Mott temperature is reached, its value increases abruptly and a distinct peak emerges, which is related with the dissociation of the sigma. For the case of [Formula: see text], the Mott dissociation is exhibited about the temperature of 189 MeV. We have also obtained the chiral phase diagram and the meson dissociation for different values of [Formula: see text]. From these results, we can state a relation between chiral symmetry restoration and Mott dissociation.

scholarly journals QCD phase diagram in a constant magnetic background

2021 ◽  
Vol 57 (6) ◽  
Author(s):  
Jens O. Andersen
Keyword(s):  
Magnetic Field ◽  
Pion Mass ◽  
Quark Condensate ◽  
Low Energy ◽  
Magnetic Catalysis ◽  
Qcd Phase Diagram ◽  
Straightforward Application ◽  
Energy Models ◽  
Njl Model ◽  
Correct Determination

AbstractMagnetic catalysis is the enhancement of a condensate due to the presence of an external magnetic field. Magnetic catalysis at $$T=0$$ T = 0 is a robust phenomenon in low-energy theories and models of QCD as well as in lattice simulations. We review the underlying physics of magnetic catalysis from both perspectives. The quark-meson model is used as a specific example of a model that exhibits magnetic catalysis. Regularization and renormalization are discussed and we pay particular attention to a consistent and correct determination of the parameters of the Lagrangian using the on-shell renormalization scheme. A straightforward application of the quark-meson model and the NJL model leads to the prediction that the chiral transition temperature $$T_{\chi }$$ T χ is increasing as a function of the magnetic field B. This is in disagreement with lattice results, which show that $$T_{\chi }$$ T χ is a decreasing function of B, independent of the pion mass. The behavior can be understood in terms of the so-called valence and sea contributions to the quark condensate and the competition between them. We critically examine these ideas as well recent attempts to improve low-energy models using lattice input.

Studies on proper time regularization and the QCD chiral phase transition

2019 ◽  
Vol 34 (01) ◽  
pp. 1950003
Author(s):  
Yu-Qiang Cui ◽  
Zhong-Liang Pan
Keyword(s):  
Phase Transition ◽  
Small Parameter ◽  
Effective Mass ◽  
Finite Temperature ◽  
Chemical Potential ◽  
Proper Time ◽  
Chiral Phase ◽  
Chiral Phase Transition ◽  
Njl Model ◽  
The Difference

We investigate the finite-temperature and zero quark chemical potential QCD chiral phase transition of strongly interacting matter within the two-flavor Nambu–Jona-Lasinio (NJL) model as well as the proper time regularization. We use two different regularization processes, as discussed in Refs. 36 and 37, separately, to discuss how the effective mass M varies with the temperature T. Based on the calculation, we find that the M of both regularization schemes decreases when T increases. However, for three different parameter sets, quite different behaviors will show up. The results obtained by the method in Ref. 36 are very close to each other, but those in Ref. 37 are getting farther and farther from each other. This means that although the method in Ref. 37 seems physically more reasonable, it loses the advantage in Ref. 36 of a small parameter dependence. In addition, we also, find that two regularization schemes provide similar results when T [Formula: see text] 100 MeV, while when T is larger than 100 MeV, the difference becomes obvious: the M calculated by the method in Ref. 36 decreases more rapidly than that in Ref. 37.

scholarly journals Imaginary Chemical Potential, NJL-Type Model and Confinement–Deconfinement Transition

Symmetry ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 562 ◽  
Author(s):  
Kouji Kashiwa
Keyword(s):  
Phase Diagram ◽  
Finite Temperature ◽  
Crucial Role ◽  
Chemical Potential ◽  
Type Model ◽  
Qcd Phase Diagram

In this review, we present of an overview of several interesting properties of QCD at finite imaginary chemical potential and those applications to exploring the QCD phase diagram. The most important properties of QCD at a finite imaginary chemical potential are the Roberge–Weiss periodicity and the transition. We summarize how these properties play a crucial role in understanding QCD properties at finite temperature and density. This review covers several topics in the investigation of the QCD phase diagram based on the imaginary chemical potential.

MESONS AND DIQUARKS IN A NJL MODEL AT FINITE TEMPERATURE AND CHEMICAL POTENTIAL

1993 ◽  
Vol 08 (07) ◽  
pp. 1295-1312 ◽  
Author(s):  
D. EBERT ◽  
YU. L. KALINOVSKY ◽  
L. MÜNCHOW ◽  
M.K. VOLKOV
Keyword(s):  
Symmetry Breaking ◽  
Chiral Symmetry ◽  
Finite Temperature ◽  
Chemical Potential ◽  
Chiral Symmetry Breaking ◽  
Baryon Number ◽  
Coupling Constants ◽  
Number Density ◽  
Njl Model

An extended NJL model with [Formula: see text] and (qq)-interactions is studied at finite temperature and baryon number density. We investigate the chiral symmetry breaking, its restoration and the behavior of meson and diquark masses, decay and coupling constants as functions of T and µ.

Proper time regularization at finite quark chemical potential

2016 ◽  
Vol 31 (14) ◽  
pp. 1650086 ◽  
Author(s):  
Jin-Li Zhang ◽  
Yuan-Mei Shi ◽  
Shu-Sheng Xu ◽  
Hong-Shi Zong
Keyword(s):  
Phase Transition ◽  
Chemical Potential ◽  
Chiral Limit ◽  
Proper Time ◽  
Quark Confinement ◽  
Chiral Phase ◽  
Chiral Phase Transition ◽  
Njl Model ◽  
Potential Case ◽  
Chiral Susceptibility

In this paper, we use the two-flavor Nambu–Jona-Lasinio (NJL) model to study the quantum chromodynamics (QCD) chiral phase transition. To deal with the ultraviolet (UV) issue, we adopt the popular proper time regularization (PTR), which is commonly used not only for hadron physics but also for the studies with magnetic fields. This regularization scheme can introduce the infrared (IR) cutoff to include quark confinement. We generalize the PTR to zero temperature and finite chemical potential case use a completely new method, and then study the chiral susceptibility, both in the chiral limit case and with finite current quark mass. The chiral phase transition is second-order in [Formula: see text] and [Formula: see text] and crossover at [Formula: see text] and [Formula: see text]. Three sets of parameters are used to make sure that the results do not depend on the parameter choice.

The two-flavor NJL model with two-cutoff proper time regularization

2014 ◽  
Vol 29 ◽  
pp. 1460232 ◽  
Author(s):  
Zhu-Fang Cui ◽  
Yi-Lun Du ◽  
Hong-Shi Zong
Keyword(s):  
Phase Transition ◽  
Finite Temperature ◽  
Chemical Potential ◽  
Proper Time ◽  
Model Parameters ◽  
Chiral Phase ◽  
Chiral Phase Transition ◽  
Regularization Scheme ◽  
Njl Model

In this paper, we use the two-flavor Nambu–Jona-Lasinio model together with the proper time regularization that has both ultraviolet and infrared cutoffs to study the chiral phase transition at finite temperature and zero chemical potential. The involved model parameters in our calculation are determined in the traditional way. Our calculations show that the dependence of the results on the choice of the parameters are really small, which can then be regarded as an advantage besides such a regularization scheme is Lorentz invariant.

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

2020 ◽  
Vol 229 (22-23) ◽  
pp. 3517-3536
Author(s):  
D. Blaschke ◽  
A. V. Friesen ◽  
Yu. L. Kalinovsky ◽  
A. Radzhabov
Keyword(s):  
Chemical Potential ◽  
Pion Mass ◽  
Heavy Ion ◽  
Bose Condensation ◽  
Chiral Phase ◽  
Qcd Phase Diagram ◽  
Scattering States ◽  
Meson Pole ◽  
Quark Models ◽  
Ion Collision

AbstractWithin 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 μB. 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 − μB plane as a proxy for the chemical freezeout line, whereby the variable x = T∕μB 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 √sNN=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.

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