Chemically non-equilibrated QGP and thermal photon elliptic flow

TL;DR

This paper explores how late chemical equilibration and in-medium modifications in the quark-gluon plasma can enhance thermal photon elliptic flow, addressing discrepancies in experimental observations.

Contribution

It introduces mechanisms involving late chemical equilibration and parton distribution modifications to improve hydrodynamic model predictions of photon flow.

Findings

Late chemical equilibration suppresses early photon emission.

In-medium modifications enhance thermal photon elliptic flow.

Models better match experimental photon flow data.

Abstract

It has been discovered in recent heavy-ion experiments that elliptic and triangular flow of direct photons are underpredicted by most hydrodynamic models. I discuss possible enhancement mechanisms based on late chemical equilibration of the QGP and in-medium modification of parton distributions. Numerical hydrodynamic analyses indicate that they suppress early photon emission and visibly enhance thermal photon elliptic flow.