Comment on ''High-temperature fermion propagator: Resummation and gauge dependence of the damping rate''

Baier, Kunstatter, and Schiff have reported the damping rate of long-wavelength fermionic excitations in high-temperature QED and QCD to be gauge-fixing dependent even within the resummation scheme due to Braaten and Pisarski. It is shown that this problem is caused by the singular nature of the on-shell expansion of the fermion self-energy in the infrared. After regularization of this expansion, the observed gauge dependence is found to pertain to the residue rather than the pole of the fermion propagator, so that in particular the damping constant comes out gauge independent, as it should