Shear Viscosity in a Gluon Gas

Abstract

The relation of the shear viscosity coefficient to the recently introduced transport rate is derived within relativistic kinetic theory. We calculate the shear viscosity over entropy ratio \eta/s for a gluon gas, which involves elastic gg-> gg perturbative QCD (PQCD) scatterings as well as inelastic gg<->ggg PQCD bremsstrahlung. For \alpha_s=0.3 we find \eta/s=0.13 and for \alpha_s=0.6, \eta/s=0.076. The small \eta/s values, which suggest strongly coupled systems, are due to the gluon bremsstrahlung incorporated.

Comments: 4 pages, 2 figures, minor corrections, 3 references added, version published in PRL