scholarly journals Bulk viscosity in strong and electroweak matter

2021 ◽  
pp. 2150067
Author(s):  
Abdel Nasser Tawfik ◽  
Carsten Greiner
Keyword(s):  
Bulk Viscosity ◽  
Top Quark ◽  
Sigma Model ◽  
Chemical Potential ◽  
Entropy Density ◽  
Linear Sigma Model ◽  
Dimensionless Quantity ◽  
Nuclear Collisions ◽  
Charged Leptons ◽  
Quark Flavors

For temperatures [Formula: see text] ranging from a few MeV up to TeV and energy density [Formula: see text] up to [Formula: see text][Formula: see text]GeV/fm3, the bulk viscosity [Formula: see text] is calculated in nonperturbation (up, down, strange, charm and bottom) and perturbation theories with up, down, strange, charm, bottom and top quark flavors, at vanishing baryon-chemical potential. To these calculations, results deduced from the effective QCD-like model, the Polyakov linear-sigma model (PLSM), are also integrated in. The PLSM merely comes up with essential contributions for the vacuum and thermal condensations of the gluons and the quarks (up, down, strange and charm flavors). Furthermore, the thermal contributions of the photons, neutrinos, charged leptons, electroweak particles and scalar Higgs boson are found very significant along the entire range of [Formula: see text] and [Formula: see text] and therefore could be well integrated in. We present the dimensionless quantity [Formula: see text], where [Formula: see text] is a perturbative scale and [Formula: see text] is the entropy density and conclude that [Formula: see text] exponentially decreases with increasing [Formula: see text]. We also conclude that the resulting [Formula: see text] with the nonperturbative and perturbative QCD contributions nonmonotonically increases with increasing [Formula: see text]. But with nearly-entire standard model contributions considered in this study, [Formula: see text] almost-linearly increases with increasing of [Formula: see text]. Apparently, these results offer a great deal to explore in astrophysics, cosmology and nuclear collisions.

scholarly journals Using the Linear Sigma Model with quarks to describe the QCD phase diagram and to locate the critical end point

2018 ◽  
Vol 172 ◽  
pp. 08002
Author(s):  
Alejandro Ayala ◽  
Jorge David Castaño-Yepes ◽  
José Antonio Flores ◽  
Saúl Hernández ◽  
Luis Hernández
Keyword(s):  
Phase Diagram ◽  
Critical Temperature ◽  
Sigma Model ◽  
Chemical Potential ◽  
Linear Sigma Model ◽  
Transition Line ◽  
Baryon Chemical Potential ◽  
First Order ◽  
Qcd Phase Diagram ◽  
Crossover Transition

We study the QCD phase diagram using the linear sigma model coupled to quarks. We compute the effective potential at finite temperature and quark chemical potential up to ring diagrams contribution. We show that, provided the values for the pseudo-critical temperature Tc = 155 MeV and critical baryon chemical potential μBc ≃ 1 GeV, together with the vacuum sigma and pion masses. The model couplings can be fixed and that these in turn help to locate the region where the crossover transition line becomes first order.

scholarly journals Locating the critical end point using the linear sigma model coupled to quarks.

2018 ◽  
Vol 172 ◽  
pp. 02003
Author(s):  
Alejandro Ayala ◽  
J. A. Flores ◽  
L. A. Hernández ◽  
S. Hernández-Ortiz
Keyword(s):  
Sigma Model ◽  
Chemical Potential ◽  
Potential Temperature ◽  
Mean Field ◽  
Field Approximation ◽  
Baryon Density ◽  
Linear Sigma Model ◽  
Mean Field Approximation ◽  
End Point ◽  
The Mean

We use the linear sigma model coupled to quarks to compute the effective potential beyond the mean field approximation, including the contribution of the ring diagrams at finite temperature and baryon density. We determine the model couplings and use them to study the phase diagram in the baryon chemical potential-temperature plane and to locate the Critical End Point.

scholarly journals SU(3) Polyakov linear-sigma model with finite isospin asymmetry: QCD phase diagram

2019 ◽  
Vol 34 (31) ◽  
pp. 1950199 ◽  
Author(s):  
Abdel Nasser Tawfik ◽  
Abdel Magied Diab ◽  
M. T. Ghoneim ◽  
H. Anwer
Keyword(s):  
Phase Structure ◽  
Sigma Model ◽  
Chemical Potential ◽  
Mean Field ◽  
Field Approximation ◽  
Linear Sigma Model ◽  
Dense Medium ◽  
Mean Field Approximation ◽  
Isospin Asymmetry ◽  
Qcd Phase Diagram

The SU(3) Polyakov linear-sigma model (PLSM) in mean-field approximation is utilized in analyzing the chiral condensates [Formula: see text], [Formula: see text], [Formula: see text] and the deconfinement order parameters [Formula: see text], [Formula: see text], at finite isospin asymmetry. The bulk thermodynamics including pressure density, interaction measure, susceptibility and second-order correlations with baryon, strange and electric charge quantum numbers are studied in thermal and dense medium. The PLSM results are confronted to the available lattice quantum chromodynamics (QCD) calculations. The excellent agreement obtained strengthens the reliability of fixing the PLSM parameters and therefore supports further predictions even beyond the scope of the lattice QCD numerical applicability. From the QCD phase structure at finite isospin chemical potential [Formula: see text], we find that the pseudocritical temperatures decrease with the increase in [Formula: see text]. We conclude that the QCD phase structure in [Formula: see text] plane seems to extend the one in [Formula: see text] plane.

PHASE TRANSITION PATTERNS OF NUCLEAR MATTER BASED ON EXTENDED LINEAR SIGMA MODEL

2013 ◽  
Vol 22 (11) ◽  
pp. 1350077 ◽  
Author(s):  
TRAN HUU PHAT ◽  
NGUYEN TUAN ANH ◽  
PHUNG THI THU HA
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Nuclear Matter ◽  
Degrees Of Freedom ◽  
Sigma Model ◽  
Chemical Potential ◽  
Linear Sigma Model ◽  
Baryon Chemical Potential ◽  
Chiral Phase ◽  
The Relationship

We study systematically various types of phase transitions in nuclear matter at finite temperature T and baryon chemical potential μ based on the extended linear sigma model with nucleon degrees of freedom. It is shown that there are three types of phase transitions in nuclear matter: the chiral symmetry nonrestoration (SNR) at high temperature, the well-known liquid–gas (LG) phase transition at sub-saturation density and the Lifshitz phase transition (LPT) from the fully-gapped state to the state with Fermi surface. Their phase diagrams are established in the (T, μ)-plane and their physical properties are investigated in detail. The relationship between the chiral phase transition and the LG phase transition in nuclear matter is discussed.

scholarly journals A comparative study on two different approaches of bulk viscosity in the Polyakov–Nambu–Jona-Lasinio model

2017 ◽  
Vol 32 (05) ◽  
pp. 1750018 ◽  
Author(s):  
Kinkar Saha ◽  
Sudipa Upadhaya ◽  
Sabyasachi Ghosh
Keyword(s):  
Comparative Study ◽  
Bulk Viscosity ◽  
Chemical Potential ◽  
Density Ratio ◽  
Mean Field ◽  
Field Approximation ◽  
Entropy Density ◽  
Mean Field Approximation ◽  
Numerical Equivalence ◽  
Pnjl Model

We have gone through a comparative study on two different kinds of bulk viscosity expressions by using a common dynamical model. The Polyakov–Nambu–Jona-Lasinio (PNJL) model in the realm of mean-field approximation, including up to eight quark interactions for 2+1 flavor quark matter, is treated for this common dynamics. We have probed the numerical equivalence as well as discrepancy of two different expressions for bulk viscosity at vanishing quark chemical potential. Our estimation of bulk viscosity to entropy density ratio follows a decreasing trend with temperature, which is observed in most of the earlier investigations. We have also extended our estimation for finite values of quark chemical potential.

scholarly journals Quark and Nuclear Matter in the Linear Chiral Meson Model

2003 ◽  
Vol 18 (18) ◽  
pp. 3189-3219 ◽  
Author(s):  
J. Berges ◽  
D.-U. Jungnickel ◽  
C. Wetterich
Keyword(s):  
Phase Transitions ◽  
Nuclear Matter ◽  
Sigma Model ◽  
Chemical Potential ◽  
Analytical Description ◽  
Baryon Number ◽  
Baryon Density ◽  
Linear Sigma Model ◽  
Density Enhancement ◽  
Quark Models

We present an analytical description of the phase transitions from a nucleon gas to nuclear matter and from nuclear matter to quark matter within the same model. The equation of state for quark and nuclear matter is encoded in the effective potential of a linear sigma model. We exploit an exact differential equation for its dependence upon the chemical potential μ associated to conserved baryon number. An approximate solution for vanishing temperature is used to discuss possible phase transitions as the baryon density increases. For a nucleon gas and nuclear matter we find a substantial density enhancement as compared to quark models which neglect the confinement to baryons. The results point out that the latter models are not suitable to discuss the phase diagram at low temperature.

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