Collective excitations of hot QCD medium in a quasiparticle description

Collective excitations of a hot QCD medium are the main focus of this article. The analysis is performed within semiclassical transport theory with isotropic and anisotropic momentum distribution functions for the gluonic and quark-antiquark degrees of freedom that constitutes the hot QCD plasma. The isotropic/equilibrium momentum distributions for gluons and quarks are based on a recent quasiparticle description of hot QCD equations of state. These effective momentum distribution functions for quasigluons and quasiquarks that encode hot QCD medium effects in terms of temperature dependent effective gluon and effective quark fugacities turned out to be isotropic in momentum. The anisotropic distributions are just the extensions of isotropic ones by stretching or squeezing them in one of the directions. The hot QCD medium effects in the model adopted here enter through the effective gluon and quark fugacities along with nontrivial dispersion relations leading to an effective QCD coupling constant. The semiclassical transport theory for computing the gluon polarization for the isotropic distributions (assuming a hot QCD medium as the ultrarelativistic system of gluons and quark/antiquarks) can straightforwardly be extended in the present case. The interactions mainly modify the Debye mass parameter and, in turn, the effective coupling in the medium. These modifications have been seen to modify the collective modes of the hot QCD plasma in a significant way.