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

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_AA=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.