Soft Photons from Off-Shell Particles in a Hot Plasma

Abstract

Considering the propagation of off-shell particles in the framework of thermal field theory, we present the general formalism for the calculation of the production rate of soft photons and dileptons from a hot plasma. This approach is first illustrated with an electrodynamic plasma. The photon production rate from strongly interacting quarks in the quark-gluon plasma, which might be formed in ultrarelativistic heavy ion collisions, is also calculated. We utilize an effective field theory incorporating dynamical chiral symmetry breaking and obtain results in the previously inaccessible regime of photon energies of the order of the plasma temperature.