Collective excitations of a hot anisotropic QCD medium with Bhatnagar-Gross-Krook collisional kernel within an effective description

TL;DR

This paper investigates how anisotropy and collisions affect collective excitations in a hot QCD medium using a semi-classical transport approach with BGK collisions and effective quasi-particle models.

Contribution

It introduces a novel analysis of collective modes in anisotropic hot QCD matter incorporating BGK collisions and a quasi-particle based effective description.

Findings

Medium effects significantly alter collective mode dispersion.

Collisions modify the plasma excitation spectrum.

Anisotropy influences the stability of collective modes.

Abstract

Collective modes of an anisotropic hot QCD medium have been studied within the semi-classical transport theory employing Bhatnagar-Gross-Krook (BGK) collisional kernel. The modeling of the isotropic medium is primarily based on a recent quasi-particle description of hot QCD equation of state where the medium effects have been encoded in effective gluon and quark/anti-quark momentum distributions that posses non-trivial energy dispersions. The anisotropic distribution functions are obtained in a straightforward the way by stretching or squeezing the isotropic ones along one of the directions. The gluon self-energy is computed using these distribution functions in a linearized transport equation with Bhatnagar-Gross-Krook (BGK) collisional kernel. Further, the tensor decomposition of gluon self-energy leads to the structure functions which eventually controls the dispersion relations and the collective mode structure of the medium. It has been seen that both the medium effects and collisions induce appreciable modifications to the collective modes and plasma excitations in the hot QCD medium.