THERMALIZATION OF BOSON PROPAGATORS IN FINITE-TEMPERATURE FIELD-THEORY

Because photons and leptons do not equilibrate in a short-lived quark-gluon plasma they provide important signals of the plasma. Radiative corrections to their propagators are quite different. The propagator for the photon (and other bosons) develops a thermal form which is correct to lowest order in the fine-structure constant alpha but to all orders in the QCD coupling alpha(s). By contrast, conservation of fermion number prevents the propagator for electrons, muons, or very heavy quarks from thermalizing at all.