Measurement of charged jet suppression in Pb-Pb collisions at √sNN=2.76 TeV

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2.76 TeV
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The ALICE collaboration at the LHC reports a measurement of the transverse momentum spectra of jets in Pb–Pb collisions at √sNN = 2.76 TeV. Jets are reconstructed from charged particles using the anti-kT jet algorithm with jet resolution parameters R of 0.2 and 0.3 in pseudo-rapidity |eta| < 0.5. The transverse momentum of charged particles is measured down to 0.15 GeV/c which gives access to the low pT fragments of the jet. Jets found in heavy-ion collisions are corrected event-by-event for average background density and on an inclusive basis (via unfolding) for residual background fluctuations. A strong suppression of jet production in central events with respect to peripheral events is observed. The suppression is found to be similar to the suppression of charged hadrons, which suggests that substantial energy is radiated at angles larger than the R considered in the analysis. The fragmentation bias on jets introduced by requiring a high pT leading particle, which rejects jets with a soft fragmentation pattern, is similar for central and peripheral events. The ratio of jets with R=0.2 and R = 0.3 is found to be similar in pp and Pb–Pb events, indicating no strong broadening of the radial jet structure.