Measurement of bottomonium production in PbPb collisions at $\sqrt{s_{NN}}$=2.76TeV with CMS

The three Y states (1S, 2S, 3S) were separated using the Compact Muon Solenoid (CMS) experimental apparatus via their dimuon decays in both pp and heavy-ion collisions. A suppression of the Y(1S), Y(2S) and Y(3S) mesons is observed in PbPb collisions at $\sqrt{s_{NN}}$ = 2.76TeV, compared to the yield in pp collisions scaled by the number of inelastic nucleon-nucleon collisions. Furthermore, a suppression of the excited Y(2S) state has been measured with respect to the Y(1S) state, expressed as a double ratio [Y(2S)/Y(1S)]$_{PbPb}$ / [Y(2S)/Y(1S)]$_{pp}$. The centrality dependence of the double ratio, as well as the nuclear modification factors (R$_{AA}$) of the Y(1S) and Y(2S) states are presented as a function of collision centrality, based on the analysis of the full data sample collected during the 2011 PbPb run, which corresponds to an integrated luminosity of 150 $\mu b^{-1}$. Upper limits for Y(3S), for both the R$_{AA}$ and the double ratio, were also calculated.