Shear Viscosity and Phase Diagram from Polyakov$-$Nambu$-$Jona-Lasinio model

TL;DR

This paper investigates how shear viscosity varies with temperature and chemical potential in the Polyakov-Nambu-Jona-Lasinio model, revealing distinctive features across phase transitions and implications for heavy-ion collision experiments.

Contribution

It provides a detailed analysis of shear viscosity dependence on spectral width and phase transitions within the PNJL model, including implications for the critical end point and experimental observables.

Findings

Shear viscosity varies strongly with spectral width of quasi-particles.

Distinctive features in shear viscosity across different phase transitions.

Variation of shear viscosity to entropy ratio analyzed for heavy-ion collisions.

Abstract

We discuss a detailed study of the variation of shear viscosity, $\eta$, with temperature and baryon chemical potential within the framework of Polyakov$-$Nambu$-$Jona-Lasinio model. $\eta$ is found to depend strongly on the spectral width of the quasi-particles present in the model. The variation of $\eta$ across the phase diagram has distinctive features for different kinds of transitions. These variations have been used to study the possible location of the Critical End Point (CEP), and cross-checked with similar studies of variation of specific heat. Finally using a parameterization of freeze-out surface in heavy-ion collision experiments, the variation of shear viscosity to entropy ratio has also been discussed as a function of the center of mass energy of collisions.