Centrality dependence of charged particle production at large transverse momentum in Pb–Pb collisions at √sNN=2.76 TeV

Abstract

The inclusive transverse momentum distributions of primary charged particles are measured in the pseudo-rapidity range |η| < 0.8 as a function of event centrality in Pb–Pb collisions at √sNN = 2.76 TeV with ALICE at the LHC. The data cover the transverse momentum range 0.15 < p_T < 50 GeV/c for nine centrality intervals from 70–80% to 0–5%. The results are presented in terms of the nuclear modification factor R_AA using a pp reference spectrum measured at the same collision energy. A strong suppression of high-p_T particles is observed, dependent on event centrality: the yield is most suppressed in central collisions (0–5%), where R_AA ≈ 0.13 at p_T = 6–7 GeV/c. For p_T = 7 GeV/c, R_AA increases significantly, reaching ≈ 0.4 for p_T > 30 GeV/c in peripheral collisions (70–80%). At large p_T, R_AA shows moderate suppression (R_AA = 0.6–0.7) and a weak p_T dependence. The measured nuclear modification factors are compared to results at lower collision energies and to theoretical model calculations.