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

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.