GAUGE (IN)DEPENDENCE OF THE FERMION DAMPING RATE IN HOT GAUGE-THEORIES

The gauge-(in)dependence problem of the fermion damping rate in hot gauge theories is carefully examined to the effective one-loop order using a recently proposed resummation method in terms of the so-called ''hard thermal loops.'' Explicit analysis is given in the case of a heavy fermion (M much greater than T), which enables us to investigate the essential point of the controversy in detail. Calculation in general covariant gauges shows in which calculation procedure we can get a gauge-parameter independent result. We also show, with explicit calculations, that the difference in the damping rate in the Landau and the Coulomb gauges is nonleading. Thus the leading-order damping rate is gauge independent within the Coulomb and general covariant gauges if an appropriate calculation procedure is employed.