Abstract
The sequential suppression of the individual Υ states in PbPb collisions with respect to their yields in pp data has been measured. The PbPb and pp datasets used in these proceedings correspond to integrated luminosities of 150/μb and 230/nb, respectively, collected by the CMS experiment at the LHC at 2.76 TeV in 2011. The relative suppression of the excited Υ states has been measured with respect to the Υ(1S) ground state, expressed as a double ratio [Υ(nS)/Υ(1S)]pbPb/[Υ(nS)/Υ(1S)]pp. The absolute suppression of the Υ(nS) yields in PbPb relative to the yields in pp scaled by the number of nucleon-nucleon collisions, RAA, is measured as a function of the collision centrality. Integrated over centrality, the RAA values for Υ(1S), Υ(2S), and the upper limit of Υ(3S) RAA are reported in this proceeding, which demonstrate the sequential suppression of the Υ(nS) states in PbPb collisions at LHC energies.
Highlights
The MIT Faculty has made this article openly available
The suppression of the individual ÇðnSÞ states in PbPb collisions with respect to their yields in pp data has been measured
The PbPb and pp data sets used in the analysis correspond to integrated luminosities of 150 bÀ1 and 230 nbÀ1, respectively, collected in 2011 by the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC), at a center-of-mass energy per nucleon pair of 2.76 TeV
Summary
Chatrchyan, S. et al “Observation of Sequential Υ Suppression in PbPb Collisions.”. Selected for a Viewpoint in Physics PHYSICAL REVIEW LETTERS week ending 30 NOVEMBER 2012
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