Thermal photon emission from the pi-rho-omega system

TL;DR

This paper calculates thermal photon emission rates from a pi-rho-omega system in hot hadronic matter using two theoretical approaches, aiming to improve the understanding of photon production in heavy-ion collisions.

Contribution

It introduces a combined relativistic kinetic theory and thermal field theory approach to compute photon emission rates, including finite-size effects and pole contributions.

Findings

Photon emission rates are comparable to existing pi rho -> pi gamma results in 1-3 GeV range.

New sources significantly contribute to total hadronic photon rates.

Results may improve the theoretical description of direct-photon spectra in heavy-ion collision experiments.

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.