The emission of electromagnetic radiation from the early stages of relativistic heavy-ion collisions

Abstract

We estimate the production of electromagnetic radiation (real and virtual photons) from the early, pre-equilibrium, stage of relativistic heavy-ion collisions. The parton dynamics are obtained as a solution of the Boltzmann equation in the Fokker-Planck diffusion limit. The photon and dilepton rates are integrated and the obtained yields are compared with those from standard sources and with available experimental data. Non-equilibrium photon spectra are predicted for Pb+Pb at $\sqrt{s_{\rm NN}} = 5.02$ TeV.