Studies of jet quenching using isolated-photon+jet correlations in PbPb and pp collisions at √ sNN=2.76 TeV
Author(s)Bauer, Gerry P.; Bendavid, Joshua L.; Busza, Wit; Butz, Erik M.; Cali, Ivan Amos; Chan, M.; Dutta, Valentina; Gomez-Ceballos, Guillelmo; Goncharov, Maxim; Hahn, Kristian Allan; Kim, Yongsun; Klute, Markus; Li, Wei; Luckey, P. David; Ma, Teng; Nahn, Steven; Paus, Christoph M. E.; Ralph, Duncan Kelley; Roland, Christof E.; Roland, Gunther M.; Rudolph, Matthew Scott; Stephans, George S. F.; Stoeckli, Fabian; Sumorok, Konstanty C.; Sung, Kevin Kai Hong; Velicanu, Dragos Alexandru; Wenger, Edward Allen; Wolf, R.; Wyslouch, Boleslaw; Xie, Si; Yang, Mingming; Yilmaz, Yetkin; Yoon, Andre S.; Zanetti, Marco; CMS Collaboration; ... Show more Show less
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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 μb−1 recorded by the CMS experiment at the LHC. For events containing an isolated photon with transverse momentum pγ[over]T >60 GeV/c and an associated jet with pJet[over]T>30 GeV/c, the photon + jet pT imbalance is studied as a function of collision centrality and compared to pp data and pythia calculations at the same collision energy. Using the pγ[over]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 pJet[over]T/pγ[over]T relative to that in the pythia reference is observed. Furthermore, significantly more pγ[over]T>60 GeV/c photons in PbPb are observed not to have an associated pJet[over]T>30 GeV/c jet, compared to the reference. However, no significant broadening of the photon + jet azimuthal correlation is observed.
DepartmentMassachusetts Institute of Technology. Department of Physics; Massachusetts Institute of Technology. Laboratory for Nuclear Science
Physics Letters B
American Physical Society
Chatrchyan, S., V. Khachatryan, A.M. Sirunyan, A. Tumasyan, W. Adam, T. Bergauer, M. Dragicevic, et al. “Studies of Jet Quenching Using Isolated-Photon+jet Correlations in PbPb and Pp Collisions At.” Physics Letters B 718, no. 3 (January 2013): 773–794.
Final published version