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

The transverse momentum (p_T) spectrum and nuclear modification factor (R_AA) of reconstructed jets in 0–10% and 10–30% central Pb–Pb collisions at √s_NN = 2.76 TeV were measured. Jets were reconstructed using the anti-k_T jet algorithm with a resolution parameter of R = 0.2 from charged and neutral particles, utilizing the ALICE tracking detectors and Electromagnetic Calorimeter (EMCal). The jet p_T spectra are reported in the pseudorapidity interval of |η_jet| < 0.5 for 40 < p_T,jet < 120 GeV/c in 0–10% and for 30 < p_T < 100 GeV/c in 10–30% collisions. Reconstructed jets were required to contain a leading charged particle with p_T > 5 GeV/c to 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 R_AA. The nuclear modification factor R_AA was found to be 0.28 ± 0.04 in 0–10% and 0.35 ± 0.04 in 10–30% collisions, independent of p_T,jet within the uncertainties of the measurement. The observed suppression is in fair agreement with expectations from two model calculations with different approaches to jet quenching.