ONE-LOOP SELF-ENERGIES AT FINITE-TEMPERATURE

The complete one-loop self energies (real and imaginary parts) for pho tons, gluons, electrons, and quarks at finite temperature are calculat ed numerically and compared to the results of the hard thermal loop (H TL) approximation used for the resummation technique of Braaten and Pi sarski. In this way some light is shed on the validity of the weak cou pling limit assumption (g much less than 1) or equivalently the high t emperature assumption, on which the HTL approximation is based. Furthe rmore, the gauge dependence of the fermion self energy beyond the HTL approximation is considered. Finally the dispersion relations followin g from the real part of the self energies are compared to the HTL resu lts. (C) 1998 Academic Press.