Photon emission from a parton gas at chemical nonequilibrium

We compute the hard photon production rate of a chemically nonequilibrated quark-gluon plasma. We assume that the plasma is already thermally equilibrated, i.e., describable by a temperature, but with a phase-space distribution that deviates from the Fermi-Bose distribution by a time dependent factor (fugacity). The photon spectrum is obtained by integrating the photon rate over the space-time evolution of the quark-gluon plasma. Some consequences for ultrarelativistic heavy ion collisions are discussed. copyright 1996 The American Physical Society