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Title: Direct photon production in high-energy nuclear collisions

Direct photons have always been considered a promising probe for the very early phases of high-energy nuclear collisions. Prompt photons reveal information about the initial state and its possible modifications in nuclei. In this context they should be one of the best probes for effects of gluon saturation. Thermal photons emitted from the produced matter in nuclear collisions carry information on the temperature of the very early phase. In particular a simultaneous measurement of yield and elliptic flow of thermal photons can put strong constraints on the early time dynamics of the system. I review the status of results on direct photon measurements at RHIC and LHC and their interpretation. Prompt photons at high p{sub T} are consistent with expectations from NLO pQCD in pp and show no strong nuclear modifications in A–A collisions. Recent analysis at RHIC has shown very intriguing results for lower p{sub T}, with high thermal photon yield and strong elliptic flow of direct photons, which are not fully understood theoretically. Also the ALICE experiment at the LHC has measured a high yield of thermal photons. Furthermore I discuss prospects for future measurements of forward direct photons at the LHC.
Authors:
 [1]
  1. Utrecht University and Nikhef, Utrecht (Netherlands)
Publication Date:
OSTI Identifier:
22499070
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1701; Journal Issue: 1; Conference: 11. conference on quark confinement and hadron spectrum, Saint Petersburg (Russian Federation), 8-12 Sep 2014; Other Information: (c) 2016 EURATOM; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ALICE DETECTOR; BROOKHAVEN RHIC; CERN LHC; COLLISIONS; GLUONS; LIMITING VALUES; MODIFICATIONS; PARTICLE PRODUCTION; PHOTONS; PROBES; YIELDS