Thermodynamic and transport properties of hot asymmetric nuclear matter within a chiral SU(3) model

Abstract

We investigate the thermodynamic and transport properties in hot nuclear matter accounting for the medium modifications of the nucleons within a chiral SU(3) model including effects from isospin asymmetry. Using the relaxation time approximation, the transport coefficients of the shear viscosity and thermal conductivity are studied. The shear viscosity, $η$, calculated within the chiral SU(3) model is observed to be smaller than the values calculated for free nucleon gas, whereas the thermal conductivity $κ$ is appreciably larger as compared to the free nucleon gas. The presence of isospin asymmetry in the medium leads to higher values of both the coefficients of shear viscosity ($η$) and thermal conductivity ($κ$), however, the effect is observed to be marginal for $η$. In the chiral SU(3) model, the effect of isospin asymmetry is observed to be larger for higher values of temperature. For T=150 MeV, there is observed to be a drop in the value of $κ$ as density is increased, contrary to the increase observed for the lower values of temperature, T=50 and 100 MeV. The shear viscosity coefficient to entropy density ratio $η/s$ drops with increasing baryon density that becomes more pronounced at higher temperatures in the chiral SU(3) model as compared to the case of a free nucleon gas. The present study of the thermodynamic as well as transport properties in hot nuclear matter is of relevance for relativistic heavy-ion collisions with different initial isospin asymmetry, in particular for the compressed baryonic matter experiment at the FAIR facility at GSI.