# Quark Matter 2014 - XXIV International Conference on Ultrarelativistic Nucleus-Nucleus Collisions

19-24 May 2014
Europe/Zurich timezone

## Systematic studies of the centrality dependence of soft photon production in $Au+Au$ collision with PHENIX

20 May 2014, 16:30
2h

### spectrum

Board: G-01
Poster Electromagnetic Probes

### Speaker

Benjamin Bannier (Stony Brook University)

### Description

Since the earliest days of Heavy Ion Physics thermal soft photon radiation emitted during the reaction had been theorized as a *smoking gun* signal for formation of a quark-gluon plasma and as a tool to characterize its properties. In recent years the existence of excess photon radiation in heavy ion collisions over the expectation from initial hard iteractions has been confirmed at both RHIC and LHC energies by PHENIX and ALICE respectively. There the radiation has been found to exhibit elliptic flow $v_2$ well above what can currently be reconciled with a picture of early emission from a plasma phase. During the 2007 and 2010 $Au+Au$ runs PHENIX has measured a high purity sample of soft photons down to $p_T>0.4\,\mathrm{GeV}/c$ using an external conversion method. We present recent systematic studies by PHENIX from that sample on the centrality dependence of the soft photon yield, and elliptic and triangular flow $v_2$ and $v_3$ in $Au+Au$ collisions which fill in the experimental picture and enable discrimination of competing soft photon production scenarios.
On behalf of collaboration: PHENIX

### Primary author

Benjamin Bannier (Stony Brook University)

 Poster