Fermion damping rate in a hot medium

TL;DR

This paper calculates the fermion damping rate in a hot medium, showing that self-consistent summation of Fock diagrams removes infrared divergences without boson screening, with analytical solutions in coupling but not in temperature.

Contribution

It introduces a self-consistent method for computing fermion damping rates that eliminates infrared divergences without requiring boson screening.

Findings

Infrared divergences are eliminated through self-consistent summation.

Solutions are analytical in the coupling constant.

Results are not analytical around zero temperature.

Abstract

In principle every excitation acquires a finite lifetime in a hot system. This nonzero spectral width is calculated self-consistently for massive fermions coupled to massless scalar, vector and pseudoscalar bosons. It is shown that the self-consistent summation of the corresponding Fock diagram for fermions eliminates all infrared divergences although the bosons are not screened at all. Our solutions for the fermion damping rate are analytical in the coupling constant, but not analytical in the temperature parameter around T=0.