The Role of Nucleons in Electromagnetic Emission Rates

TL;DR

This paper investigates how nucleons influence electromagnetic emission rates in a thermalized hadronic gas, highlighting the importance of proper pi-N background treatment and the dilute nature of the gas for interpreting heavy-ion collision signals.

Contribution

It introduces a background constrained by unitarity and chiral symmetry, clarifying the role of nucleons and baryon density effects on emission rates.

Findings

Nucleons significantly affect electromagnetic emission rates.

Proper pi-N background treatment is crucial for accurate modeling.

The hadronic gas can be considered dilute under the studied conditions.

Abstract

Electromagnetic emission rates from a thermalized hadronic gas are important for the interpretation of dilepton signals from heavy-ion collisions. Although there is a consensus in the literature about rates for a pure meson gas, qualitative differences appear with a finite baryon density. We show this to be essentially due to the way in which the pi-N background is treated in regards to the nucleon resonances. Using a background constrained by unitarity and broken chiral symmetry, it is emphasized that the thermalized hadronic gas can be considered dilute.