Direct photon production in relativistic heavy-ion collisions -- a theory update

TL;DR

This paper reviews recent theoretical advances in modeling photon production in relativistic heavy-ion collisions, emphasizing new approaches to photon emission from non-equilibrium quark-gluon plasma and addressing the photon flow puzzle.

Contribution

It introduces a hybrid modeling approach combining IP-Glasma, fluid dynamics, and hadronic cascade, and discusses recent developments in photon emission theory from non-equilibrium media.

Findings

Improved modeling of hadron dynamics in heavy-ion collisions.

Insights into the photon flow puzzle.

Development of non-equilibrium photon emission theories.

Abstract

For tomographic studies of relativistic nuclear collisions and of the quark-gluon plasma, photons (real and virtual) are unique. They are the only probes than can be both soft and penetrating. First we report on advances in modelling the hadron dynamics of heavy-ion collisions using a hybrid approach which consists of IP-Glasma, relativistic fluid dynamics, and hadronic cascade components. We briefly discuss the "photon flow puzzle", and then focus on a recent development in the theory of photon emission from a non-equilibrium, strongly interacting medium.