Observation and studies of jet quenching in PbPb collisions at root s(NN)=2.76 TeV

Jet production in PbPb collisions at a nucleon-nucleon center-of-mass energy of 2.76 TeV was studied with the Compact Muon Solenoid (CMS) detector at the LHC, using a data sample corresponding to an integrated luminosity of 6.7 mu b(-1). Jets are reconstructed using the energy deposited in the CMS calorimeters and studied as a function of collision centrality. With increasing collision centrality, a striking imbalance in dijet transverse momentum is observed, consistent with jet quenching. The observed effect extends from the lower cutoff used in this study (jet p(T) = 120 GeV/c) up to the statistical limit of the available data sample (jet p(T) approximate to 210 GeV/c). Correlations of charged particle tracks with jets indicate that the momentum imbalance is accompanied by a softening of the fragmentation pattern of the second most energetic, away-side jet. The dijet momentum balance is recovered when integrating low transverse momentum particles distributed over a wide angular range relative to the direction of the away-side jet. RI Hektor, Andi/G-1804-2011; Wulz, Claudia-Elisabeth/H-5657-2011; Chen, Jie/H-6210-2011; Bolton, Tim/A-7951-2012; Stahl, Achim/E-8846-2011; Yang, Fan/B-2755-2012; Krammer, Manfred/A-6508-2010; Tinoco Mendes, Andre David/D-4314-2011; Petrushanko, Sergey/D-6880-2012; Lokhtin, Igor/D-7004-2012; Kodolova, Olga/D-7158-2012; Belyaev, Andrey/E-1540-2012; Katkov, Igor/E-2627-2012; Snigirev, Alexander/D-8912-2012; Tomei, Thiago/E-7091-2012; Focardi, Ettore/E-7376-2012; Novaes, Sergio/D-3532-2012; Padula, Sandra /G-3560-2012; Flix, Josep/G-5414-2012; Fruhwirth, Rudolf/H-2529-2012; Azzi, Patrizia/H-5404-2012; Torassa, Ezio/I-1788-2012

Jet production in PbPb collisions at a nucleon-nucleon center-of-mass energy of 2.76 TeV was studied with the Compact Muon Solenoid (CMS) detector at the LHC, using a data sample corresponding to an integrated luminosity of 6.7μb-1. Jets are reconstructed using the energy deposited in the CMS calorimeters and studied as a function of collision centrality. With increasing collision centrality, a striking imbalance in dijet transverse momentum is observed, consistent with jet quenching. The observed effect extends from the lower cutoff used in this study (jet pT=120 GeV/c) up to the statistical limit of the available data sample (jet pT≈210 GeV/c). Correlations of charged particle tracks with jets indicate that the momentum imbalance is accompanied by a softening of the fragmentation pattern of the second most energetic, away-side jet. The dijet momentum balance is recovered when integrating low transverse momentum particles distributed over a wide angular range relative to the direction of the away-side jet.