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

Abstract The inclusive transverse momentum ( p T ) 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 s NN = 2.76 TeV with ALICE at the LHC. The data are presented in the p T range 0.15 p T 50 GeV / c for nine centrality intervals from 70–80% to 0–5%. The results in Pb–Pb are presented in terms of the nuclear modification factor R AA using a pp reference spectrum measured at the same collision energy. We observe that the suppression of high- p T particles strongly depends on event centrality. The yield is most suppressed in central collisions (0–5%) with R AA ≈ 0.13 at p T = 6 – 7 GeV / c . Above p T = 7 GeV / c , there is a significant rise in the nuclear modification factor, which reaches R AA ≈ 0.4 for p T > 30 GeV / c . In peripheral collisions (70–80%), only moderate suppression ( R A A = 0.6 – 0.7 ) and a weak p T dependence is observed. The measured nuclear modification factors are compared to other measurements and model calculations.