Electromagnetic radiation from nuclear collisions at RHIC energies

TL;DR

This paper models electromagnetic radiation from heavy-ion collisions at RHIC using relativistic hydrodynamics, accounting for various photon sources and jet energy loss, and compares results with experimental data.

Contribution

It introduces a comprehensive calculation of photon spectra from multiple sources in heavy-ion collisions, including jet-medium interactions and thermal radiation, with jet energy loss incorporated via the AMY formalism.

Findings

Calculated photon spectra and R_AA match RHIC data.

Identified the relative importance of different photon sources.

Predicted azimuthal anisotropy v_2 consistent with measurements.

Abstract

The hot and dense strongly interacting matter created in collisions of heavy nuclei at RHIC energies is modeled with relativistic hydrodynamics, and the spectra of real and virtual photons produced at mid-rapidity in these events are calculated. Several different sources are considered, and their relative importance is compared. Specifically, we include jet fragmentation, jet-plasma interactions, the emission of radiation from the thermal medium and from primordial hard collisions. Our calculations consistently take into account jet energy loss, as evaluated in the AMY formalism. We obtain results for the spectra, the nuclear modification factor (R_AA), and the azimuthal anisotropy (v_2) that agree with the photon measurements performed by the PHENIX collaboration at RHIC.