Measurement of bottomonium production in PbPb collisions at √sNN=2.76 TeV with CMS

The three Upsilon 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 Upsilon(1S), Upsilon(2S) and Upsilon(3S) mesons is observed in PbPb collisions at root s(NN) = 2.76 TeV, compared to the yield in pp collisions scaled by the number of inelastic nucleon-nucleon collisions. Furthermore, a suppression of the excited Upsilon(2S) state has been measured with respect to the Upsilon(1S) state, expressed as a double ratio [Upsilon(2S)/Upsilon(1s)](PbPb)/[Upsilon(2S)/Upsilon(1S)](pp). The centrality dependence of the double ratio, as well as the nuclear modification factors (R-AA) of the Upsilon(1S) and Upsilon(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 Upsilon(35), for both the R-AA and the double ratio, were also calculated.