Studies of jet quenching using isolated-photon+jet correlations in PbPb and pp collisions at √ sNN=2.76 TeV

Studies of jet quenching using isolated-photon+jet correlations in PbPb and pp collisions at √ sNN=2.76 TeV

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 experi...

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Bibliographic Details
Main Authors: Bendavid, Joshua L., Busza, Wit, Butz, Erik M., Cali, Ivan Amos, Chan, M., Dutta, Valentina, Gomez-Ceballos, Guillelmo, Goncharov, Maxim, Hahn, Kristian Allan, Klute, Markus, Ma, Teng, Nahn, Steven, Paus, Christoph M. E., Ralph, Duncan Kelley, Rudolph, Matthew Scott, Stephans, George S. F., Stoeckli, Fabian, Sung, Kevin Kai Hong, Velicanu, Dragos Alexandru, Wenger, Edward Allen, Wyslouch, Boleslaw, Xie, Si, Yang, Mingming, Yilmaz, Yetkin, Zanetti, Marco, CMS Collaboration, Bauer, Gerry P, Kim, Y., Li, W., Luckey Jr, P David, Roland, Christof E, Roland, Gunther M, Sumorok, Konstanty C, Wolf, Roger, Yoon, A. S.
Other Authors: Massachusetts Institute of Technology. Department of Physics
Format: Article
Language:en_US
Published: American Physical Society 2014
Online Access:http://hdl.handle.net/1721.1/91684
https://orcid.org/0000-0002-3831-9071
https://orcid.org/0000-0003-3106-4894
https://orcid.org/0000-0001-6332-5839
https://orcid.org/0000-0001-8983-2169
https://orcid.org/0000-0002-1260-777X
https://orcid.org/0000-0002-6047-4211
https://orcid.org/0000-0003-3681-0649
https://orcid.org/0000-0002-0869-5631
Description
Summary: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.

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