Studies of jet quenching using isolated-photon + jet correlations in PbPb and pp collisions at sqrt(s[NN]) = 2.76 TeV

Abstract

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 inverse microbarns recorded by the CMS experiment at the LHC. For events containing an isolated photon with transverse momentum pt(gamma) > 60 GeV and an associated jet with pt(Jet) > 30 GeV, 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 pt(gamma) 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 pt(Jet)/pt(gamma) relative to that in the PYTHIA reference is observed. Furthermore, significantly more pt(gamma) > 60 GeV photons in PbPb are observed not to have an associated pt(Jet) > 30 GeV jet, compared to the reference. However, no significant broadening of the photon + jet azimuthal correlation is observed.

Submitted to Physics Letters B

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Cited by in corpus (12)

• Jet physics in heavy-ion collisions
• Measurement of jet fragmentation in PbPb and pp collisions at sqrt(s[NN]) = 2.76 TeV
• Measurement of jet suppression in central Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV
• Measurement of inclusive jet charged-particle fragmentation functions in Pb+Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV with the ATLAS detector
• Hadron spectra, flow and correlations in PbPb collisions at the LHC: interplay between soft and hard physics
• Exceptional thermodynamics: The equation of state of G(2) gauge theory
• Exploring the properties of the phases of QCD matter - research opportunities and priorities for the next decade
• Theory of Jet Quenching in Ultra-Relativistic Nuclear Collisions
• Hydrodynamics and Jets in Dialogue
• Perturbative probes of QCD matter at the Large Hadron Collider
• The Strongly Interacting Quark Gluon Plasma at RHIC and LHC
• Jet modification in hot and dense QCD matter