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arXiv · 1106.4306

Calculation of shear viscosity using Green-Kubo relations within a parton cascade

C. Wesp·A. El·F. Reining·Z. Xu·I. Bouras·C. Greiner
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Abstract

The shear viscosity of a gluon gas is calculated using the Green-Kubo relation. Time correlations of the energy-momentum tensor in thermal equilibrium are extracted from microscopic simulations using a parton cascade solving various Boltzmann collision processes. We find that the pQCD based gluon bremsstrahlung described by Gunion-Bertsch processes significantly lowers the shear viscosity by a factor of 3-8 compared to elastic scatterings. The shear viscosity scales with the coupling as 1/(alpha_s^2\log(1/alpha_s)). For a constant coupling constant the shear viscosity to entropy density ratio has no dependence on temperature. Replacing the pQCD-based collision angle distribution of binary scatterings by an isotropic form decreases the shear viscosity by a factor of 3.

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C. Wesp, A. El, F. Reining, Z. Xu, I. Bouras, C. Greiner. 2011-06-21. Calculation of shear viscosity using Green-Kubo relations within a parton cascade. https://doi.org/10.1103/physrevc.84.054911

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