Electromagnetic Radiation from Baryon-Rich Matter in Heavy-Ion Collisions

TL;DR

This paper investigates electromagnetic radiation, including photons and dileptons, produced in heavy-ion collisions at RHIC and SPS energies using advanced multistage modeling, providing insights into the quark-gluon plasma properties.

Contribution

It introduces a comprehensive multistage simulation framework calibrated to experimental data, incorporating NLO thermal QCD rates to analyze electromagnetic emissions across collision energies.

Findings

Photon yield and elliptic flow vary with collision energy.

Effective temperature of quark-gluon plasma is extracted from dilepton spectra.

Model results are consistent with STAR and PHENIX experimental data.

Abstract

We perform a study of electromagnetic radiation in heavy-ion collisions at Relativistic Heavy Ion Collider (RHIC) Beam Energy Scan (BES) and SPS energies using the iEBE-MUSIC framework, which includes 3D dynamical Monte Carlo Glauber initial conditions, MUSIC (3+1)D viscous relativistic hydrodynamics, and the UrQMD hadronic afterburner. The multistage modeling has been calibrated to hadronic data at RHIC-BES energies using a Bayesian analysis. Integrating the thermal photon emission rates with the medium evolution, we study the direct photon yield and elliptic flow and how they vary with collision energy and emission source. We compare with results obtained by the STAR and PHENIX Collaborations. We employ next-to-leading order thermal QCD dilepton emission rates to compute dilepton invariant mass spectra and extract the effective temperature of the quark-gluon plasma at different collision energies.