Thermal photon emission from the pi-rho-omega system

Abstract: We investigate thermal photon emission rates in hot hadronic matter from a system consisting of pi, rho, and omega mesons. The rates are calculated using both relativistic kinetic theory with Born diagrams as well as thermal field theory at the two-loop level. This enables us to cross-check our calculations and to manage a pole contribution that arises in the Born approximation corresponding to the omega -> pi^0 gamma radiative decay. After implementing hadronic form factors to account for finite-size corrections, we find that the resulting photo-emission rates are comparable to existing results from pi rho -> pi gamma processes in the energy regime of 1-3 GeV. We expect that our new sources will provide a non-negligible contribution to the total hadronic rates, thereby enhancing calculated thermal photon spectra from heavy-ion collisions, which could improve the description of current direct-photon data from experiment.