SCREENING OF MASS SINGULARITIES AND FINITE SOFT-PHOTON PRODUCTION-RATE IN HOT QCD

The production rate of a soft photon from a hot quark-gluon plasma is computed to leading order at logarithmic accuracy. The canonical hard- thermal-loop resummation scheme leads to a logarithmically divergent p roduction rate due to mass singularities. We show that these mass sing ularities are screened by employing the effective hard-quark propagato r, which is obtained through resummation of the one-loop self-energy p art in a self-consistent manner. The damping-rate part of the effectiv e hard-quark propagator, rather than the thermal-mass part, plays the dominant role of screening mass singularities. Diagrams including phot on(hard-)quark vertex corrections also yield the leading contribution to the production rate.