Detailed measurements of bottomonium suppression in PbPb collisions at 2.76 TeV with CMS

The three $\Upsilon(1S, 2S, 3S)$ states can be separated using the 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 $\sqrt{s_{NN}}$ = 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 $\Upsilon$ states has been measured with respect to the $\Upsilon$ ground state, expressed as a double ratio [$\Upsilon(nS)$/$\Upsilon(1S)$]$_{PbPb}$ / [$\Upsilon(nS)$/$\Upsilon(1S)$]$_{pp}$ with n = 2, 3, and 2 + 3. 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 and the 2010 pp run, which corresponds to an integrated luminosity of 150 $\mu b^{-1}$ and 231 $nb^{-1}$ respectively. The three \U~states suppression pattern is ordered as \U(3S) $>$ \U(2S) $>$ \U(1S).