Lifetime of Quasiparticles in Hot QED Plasmas

The calculation of the lifetime of quasiparticles in a QED plasma at high temperature remains plagued with infrared divergences, even after including the screening corrections. We argue that the self-energy diagrams which give the dominant divergences contain no internal fermion loops, but an arbitrary number of magnetostatic photon lines. A generalization of the Bloch-Nordsieck approximation allows us to resum all the singular contributions of such diagrams, and to obtain the correct long time behavior of the retarded fermion propagator: S_R\(t\)~exp\{-αTt lnω_pt\}, where ω_p = eT/3 is the plasma frequency and α = e²/4π.