Centrality and $p_{T}$ dependence of charged particle $\R_{AA}$ in PbPb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV

The transverse momentum ($p_T$) spectra of charged particles is measured by CMS as a function of collision centrality in PbPb collisions at $\sqrt{s_{_{NN}}} = 2.76$ TeV. The results are compared to a pp reference spectrum, constructed by interpolation between $\sqrt{s}$ = 0.9 and 7 TeV measurements. The nuclear modification factor ($R_{AA}$) is constructed by dividing the PbPb $p_T$ spectrum, normalized to the number of binary collisions ($N_{coll}$), by the pp spectrum. Measured $R_{AA}$ in 0--5\% centrality bin is compared to several theoretical predictions.