Measurement of isolated photon production in $pp$ and PbPb collisions at $\sqrt{s_{NN}}=2.76$ TeV

• Main Author: CMS collaboration (2266 authors)
• Publication Date: 2013
• Other Authors: Hollar, Jonathan, Almeida, Nuno, Bargassa, Pedrame, David Tinoco Mendes, Andre, Faccioli, Pietro, Ferreira Parracho, Pedro Guilherme, Gallinaro, Michele, Musella, Pasquale, Nayak, Aruna, Pela, Joao, Ribeiro, Pedro Quinaz, Seixas, Joao, Varela, Joao, Vischia, Pietro, Lloret Iglesias, Lara, Rodrigues Antunes, Joao, Silva, Pedro, Leonardo, Nuno
• Format: Article
• Language: eng
• Source: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
• Download full: http://dx.doi.org/10.1016/j.physletb.2012.02.077; http://hdl.handle.net/10400.26/27734

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.