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

The inclusive transverse momentum (pT) distributions of primary charged particles are measured in the pseudo-rapidity range |?|<0.8 as a function of event centrality in Pb-Pb collisions at vsNN=2.76TeV with ALICE at the LHC. The data are presented in the pTrange 0.15<pT<50GeV/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 RAAusing a pp reference spectrum measured at the same collision energy. We observe that the suppression of high-pTparticles strongly depends on event centrality. The yield is most suppressed in central collisions (0-5%) with RAA˜0.13 at pT=6-7GeV/c. Above pT=7GeV/c, there is a significant rise in the nuclear modification factor, which reaches RAA˜0.4 for pT>30GeV/c. In peripheral collisions (70-80%), only moderate suppression (RAA=0.6-0.7) and a weak pTdependence is observed. The measured nuclear modification factors are compared to other measurements and model calculations. © 2013 CERN.