Shear and bulk viscosity of high-temperature gluon plasma
- Received Date: 2018-02-26
- Available Online: 2018-06-05
Abstract: We calculate the shear viscosity (η) and bulk viscosity (ζ) to entropy density (s) ratios η/s and ζ/s of a gluon plasma system in kinetic theory, including both the elastic gg↔gg forward scattering and the inelastic soft gluon bremsstrahlung gg↔ggg processes. Due to the suppressed contribution to η and ζ in the gg↔gg forward scattering and the effective g↔gg gluon splitting, Arnold, Moore and Yaffe (AMY) and Arnold, Dogan and Moore (ADM) have got the leading order computations for η and ζ in high-temperature QCD matter. In this paper, we calculate the correction to η and ζ in the soft gluon bremsstrahlung gg↔ggg process with an analytic method. We find that the contribution of the collision term from the gg↔ggg soft gluon bremsstrahlung process is just a small perturbation to the gg↔gg scattering process and that the correction is at~5% level. Then, we obtain the bulk viscosity of the gluon plasma for the number-changing process. Furthermore, our leading-order result for bulk viscosity is the formula ζ∝(αs2T3)/(lnαs-1) in high-temperature gluon plasma.