Production of Photons and Dileptons in the Glasma

TL;DR

This paper investigates photon and dilepton production during the early Glasma stage in heavy ion collisions, showing qualitative agreement with experimental data and suggesting possible Bose condensate contributions.

Contribution

It provides a detailed analysis of electromagnetic emissions during the Glasma phase, highlighting features that align with experimental observations and proposing new insights into early-stage collision dynamics.

Findings

Transverse momentum spectra match experimental data.

Intermediate mass dileptons agree with estimates.

Evidence suggests emissions from a Bose condensate.

Abstract

We study the production of photons and dileptons during the pre-equilibrium Glasma stage in heavy ion collisions and discuss the implications in light of the PHENIX data. We find that the measured distributions of such electromagnetic emissions, while having some features not well understood if hypothesized to entirely arise from a thermalized Quark-Gluon Plasma, have some qualitative features that might be described after including effects from a thermalizing Glasma. The shape and centrality dependence of the transverse momentum spectra of the so-called "thermal photons" are well described. The mass and transverse momentum dependence of intermediate mass dileptons also agree with our estimates. The low transverse momenta from which the excessive dileptons (in low to intermediate mass region) arise is suggestive of emissions from a Bose condensate. We also predict the centrality dependence of dilepton production. Uncertainties in the current approach and improvements in the future are discussed.