Chemically non-equilibrated QGP and thermal photon elliptic flow

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.

Comments: 4 pages, 5 figures - To appear in the conference proceedings for Hard Probes 2015, June 29-July 3, McGill University, Montreal, Canada