ϒ production in Pb+Pb collisions at √sNN=2.76 TeV

The heavy ion collisions are performed to study the interaction of matter at extreme temperatures and densities where it is expected to be in the form of Quark Gluon Plasma (QGP), a state where color degrees of freedom are dominant. One of the expected signal of this phase is the suppression of quarkonium states, both from the charmonium (J/ψ , ψ', χc, etc.) and bottomonium families (ϒ(1S, 2S, 3S), χb, etc) due to the color screening produced by the surrounding light quarks and gluons. Measurements of the ϒ(1S) absolute suppression and the relative suppression of (2S)+ϒ(3S) to ϒ(1S) were recently reported by CMS experiment for integrated luminosity 7.28 μb-1. In this paper, an update of these measurements is reported, utilizing 150 μb-1 of PbPb data and 231 nb-1 of pp data, collected in 2011 by CMS at √sNN = 2.76 TeV. This larger PbPb dataset together with the good momentum resolution of the CMS detector allow for separating the ϒ excited states in the heavy-ion environment and exploring centrality dependence of their production