The Hot Nonperturbative Gluon Plasma Is an Almost Ideal Colored Liquid

Abstract

We study properties of a gluon plasma above the critical temperature Tc in a generalized quasiparticle approach with a Lorentz spectral function. The model parameters are determined by a fit of the entropy s to lattice QCD data. The effective degrees of freedom are found to be rather heavy and of a sizable width. With the spectral width being closely related to the interaction rate, we find a large effective cross section, which is comparable to the typical distance squared of the quasiparticles. This suggests that the system should be viewed as a liquid as also indicated by an estimate of the plasma parameter Gamma. Furthermore, within the quasiparticle approach we find a very low viscosity to entropy ratio, eta/s approximately 0.2 for T > 1.05 Tc, supporting the recent conjecture of an almost ideal quark-gluon liquid seen at RHIC.