Speaker
camelia mironov
(LLR/Ecole polytechnique)
Description
The Compact Muon Solenoid (CMS) is fully equipped to measure hard probes in the di-muon decay channel in the high multiplicity environment of nucleus-nucleus collisions. Such probes are especially relevant for studying the quark-gluon plasma since they are produced at early times and propagate through the medium, mapping its evolution. CMS has measured the nuclear modification factors of Y(1S) in PbPb collisions at $\sqrt{s_{NN}} = 2.76$ TeV. A suppression of Y(1S) mesons is observed in PbPb collisions, compared to the yield in pp collisions scaled by the number of inelastic nucleon-nucleon collisions. Furthermore, a suppression of the excited Y-states has been measured with respect to the Y(1S) state, expressed in a double ratio [Y(2S+3S)/Y(1S)]$_{PbPb}$/[Y(2S+3S)/Y(1S)]$_{pp}$ which is found to be $0.31^{+0.19}_{-0.15}(stat.)\pm0.03(syst.)$. Results from the 2010 data taking period are reported and an outlook on the 2011 data analysis will be given.
Summary
The LHC opens up a new era of precision measurements of the bottomonium family of states. We report the results of the first detailed upsilon studies in heavy-ion collisions, obtained with the CMS experiment.
Primary author
camelia mironov
(LLR/Ecole polytechnique)
