Measurement of isolated photon production in pp and PbPb collisions at √SNN=2.76 TeV
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 |η|<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.
CMS; physics; heavy-ions; photons