Measurement of isolated-photon+jet correlations in PbPb collisions at image with CMS

A measurement of the transverse momentum balance in isolated-photon+jet pairs in PbPb collisions is described. The analysis is performed using a dataset recorded by the CMS experiment at the LHC from PbPb collisions at View the MathML sourcesNN=2.76 TeV, corresponding to an integrated luminosity of ∫Ldt=150μb−1∫Ldt=150μb−1. For events containing an isolated photon with View the MathML sourcepTγ>60 GeV/c and an associated jet with View the MathML sourcepTJet>30 GeV/c, the photon+jet transverse momentum balance is studied as a function of collision centrality and compared to pp data and PYTHIA calculations. Using the isolated photon as the probe of the partonic energy at production, this measurement allows an unbiased characterization of the in-medium parton energy loss. With increasing collision centrality, a significant decrease in the ratio View the MathML sourcepTJet/pTγ relative to the pp reference is observed.