Shear viscosity to entropy density ratio in the Boltzmann-Uehling-Uhlenbeck model

S. X. Li, D. Q. Fang, Y. G. Ma, C. L. Zhou

Published 2011-07-14, updated 2011-08-11Version 2

The ratio of shear viscosity ($\eta$) to entropy density ($s$) for an equilibrated system is investigated in intermediate energy heavy ion collisions below 100$A$ MeV within the framework of the Boltzmann-Uehling-Uhlenbeck (BUU) model . After the collision system almost reaches a local equilibration, the temperature, pressure and energy density are obtained from the phase space information and {$\eta/s$} is calculated using the Green-Kubo formulas. The results show that {$\eta$}/$s$ decreases with incident energy and tend towards a smaller value around 0.5, which is not so drastically different from the BNL Relativistic Heavy Ion Collider results in the present model.