Shear viscosity to entropy density ratio in BUU transport model

Abstract

Shear viscosity (eta) is a basic transport coefficient of the medium. In this work, we calculate shear viscosity to entropy density ratio (eta/S) of an equilibrated system in intermediate energy heavy ion collisions within the framework of the Boltzmann-Uehling-Uhlenbeck model (BUU) model. After the equilibration of Au + Au system at central collision in a fixed volume is reached, temperature, pressure and energy density are extracted by the phase space information and then eta/S is calculated using the Green-Kubo formulas. The results show that eta/S drops with the incident energy and its value is not so drastically different from the RHIC results.