On the fluctuation-dissipation theorem for soft fermionic excitations in a hot QCD plasma

TL;DR

This paper derives the fluctuation-dissipation theorem for soft fermionic excitations in a hot QCD plasma using two different methods, confirming the consistency and validity of a pseudoclassical model for such systems.

Contribution

It presents two derivations of the FDT for soft fermions in a hot plasma, demonstrating their agreement and supporting the pseudoclassical model's validity.

Findings

Both derivations of the FDT coincide perfectly.

The pseudoclassical model is validated for describing soft fermionic excitations.

The methods confirm the FDT's applicability in a hot QCD plasma.

Abstract

We discuss two ways of deriving the fluctuation-dissipation theorem (FDT) for soft fermion excitations in a hot non-Abelian plasma being in a thermal equilibrium. The first of them is based on the extended (pseudo)classical model in describing a quark-gluon plasma suggested in [Yu.A. Markov, M.A. Markova, Nucl. Phys. A {\bf 784} (2007) 443], while the second one rests on the standard technique of calculation of the FDT for thermodynamically equilibrium systems. We show that full accounting all subtleties that are common to the fermion system under consideration, results in perfect coincidence of thus obtained FDTs. This provides a rather strong argument for the validity of the pseudoclassical model suggested.