2012/05/31 by S. Chatrchyan, CMS Collaboration, V. Khachatryan +98
Engineering · Physics and Astronomy · #High-Energy Particle Collisions Research #Nuclear reactor physics and engineering #Quantum Chromodynamics and Particle Interactions #hep-ex #nucl-ex
paper · pdf · doi:10.1016/j.physletb.2012.11.003
published as Phys. Lett. B 718 (2013) 773 · Submitted to Physics Letters B
openalex publication_date 2012/11/07 · arxiv created 2013/01/24 · arxiv updated 2013/01/25 · openalex created_date 2021/08/02 · openalex updated_date 2026/08/04
Results from the first study of isolated-photon + jet correlations in relativistic heavy ion collisions are reported. The analysis uses data from PbPb collisions at a centre-of-mass energy of 2.76 TeV per nucleon pair corresponding to an integrated luminosity of 150 b -1 recorded by the CMS experiment at the LHC. For events containing an isolated photon with transverse momentum p T > 60 GeV/c and an associated jet with p Jet T > 30 GeV/c, the photon + jet p T imbalance is studied as a function of collision centrality and compared to pp data and pythia calculations at the same collision energy. Using the p T of the isolated photon as an estimate of the momentum of the associated parton at production, this measurement allows an unbiased characterisation of the in-medium parton energy loss. For more central PbPb collisions, a significant decrease in the ratio p Jet T /p T relative to that in the pythia reference is observed. Furthermore, significantly more p T > 60 GeV/c photons in PbPb are observed not to have an associated p Jet T > 30 GeV/c jet, compared to the reference. However, no significant broadening of the photon + jet azimuthal correlation is observed.