Measurement of isolated photon production in pp and PbPb collisions at image with CMS

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