  Baier et al. 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 infra-red. Its regularization reveals that the
alleged gauge dependence pertains 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.
