Measurement of isolated photon production in pp and PbPb collisions at sqrt(sNN) = 2.76 TeV

CMS [UCL] Basegmez, Suzan [UCL] Bruno, Giacomo [UCL] Caudron, Julien [UCL] Ceard, Ludivine [UCL] De Favereau De Jeneret, Jerome [UCL] Delaere, Christophe [UCL] Favart, Denis [UCL] Forthomme, Laurent [UCL] Giammanco, Andrea [UCL] Grégoire, Ghislain [UCL] Hollar, Jonathan [UCL] Lemaitre, Vincent [UCL] Liao, Junhui [UCL] Militaru, Otilia [UCL] Nuttens, Claude [UCL] Pagano, Davide [UCL] Pin, Arnaud [UCL] Piotrzkowski, Krzysztof [UCL] Schul, Nicolas [UCL] et al.

Isolated photon production is measured in proton-proton and lead-lead collisions at nucleon-nucleon centre-of-mass energies of 2.76 TeV in the pseudorapidity range |eta|<1.44 and transverse energies ET between 20 and 80 GeV with the CMS detector at the LHC. The measured ET spectra are found to be in good agreement with next-to-leading-order perturbative QCD predictions. The ratio of PbPb to pp isolated photon ET-differential yields, scaled by the number of incoherent nucleon-nucleon collisions, is consistent with unity for all PbPb reaction centralities.