Measurement of jet suppression in central Pb–Pb collisions at √sNN=2.76 TeV

Abstract

The transverse momentum(pT) spectrum and nuclear modification factor (RAA) of reconstructed jets in 0–10% and 10–30% central Pb–Pb collisions at √sNN=2.76TeVwere measured. Jets were reconstructed using the anti-kTjet algorithm with a resolution parameter of R =0.2from charged and neutral particles, utilizing the ALICE tracking detectors and Electromagnetic Calorimeter (EMCal). The jet pTspectra are reported in the pseudorapidity interval of |ηjet| <0.5for 40 <pT,jet<120GeV/cin 0–10% and for 30 <pT,jet<100GeV/cin 10–30% collisions. Reconstructed jets were required to contain a leading charged particle with pT>5GeV/cto suppress jets constructed from the combinatorial background in Pb–Pb collisions. The leading charged particle requirement applied to jet spectra both in pp and Pb–Pb collisions had a negligible effect on the RAA. The nuclear modification factor RAAwas found to be 0.28 ±0.04in 0–10% and 0.35 ±0.04in 10–30% collisions, independent of pT,jetwithin the uncertainties of the measurement. The observed suppression is in fair agreement with expectations from two model calculations with different approaches to jet quenching.