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

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