# Hadronic Production of Thermal Photons

## TL;DR

This paper reevaluates thermal photon emission from hot hadronic matter near the QGP transition, incorporating new channels and effects, and compares the results with experimental data from heavy-ion collisions.

## Contribution

It introduces additional production channels and hadronic form factor effects, providing a more realistic photon emission rate for heavy-ion collision applications.

## Key findings

- Omega meson t-channel exchange significantly contributes above 1.5 GeV
- Hadronic photon yields are moderate with strangeness effects
- Combined emission rates align with experimental spectra at SPS, RHIC, LHC

## Abstract

We study the thermal emission of photons from hot and dense strongly interacting hadronic matter at temperatures close to the expected phase transition to the Quark-Gluon Plasma (QGP). Earlier calculations of photon radiation from ensembles of interacting mesons are re-examined with additional constraints, including new production channels as well as an assessment of hadronic form factor effects. Whereas strangeness-induced photon yields turn out to be moderate, the hitherto not considered t-channel exchange of omega mesons is found to contribute appreciably for photon energies above ~1.5 GeV. The role of baryonic effects is assessed using existing many-body calculations of lepton pair production. We argue that our combined results constitute a rather realistic emission rate, appropriate for applications in relativistic heavy-ion collisions. Supplemented with recent evaluations of QGP emission, and an estimate for primordial (hard) production, we compute photon spectra at SPS, RHIC and LHC energies.