Speaker
Torsten Dahms
(Ecole Polytechnique (FR))
Description
The Compact Muon Solenoid (CMS) has measured various quarkonium states via their decays into muon pairs in pp and PbPb collisions at sqrt(s_NN) = 2.76 TeV. Quarkonia are especially relevant for studying the quark-gluon plasma since they are produced at early times of the collision and propagate through the medium, mapping its evolution. The most recent results on the production of prompt J/psi, psi(2S) and the first three Y states will be presented. At high transverse momenta (pT>6.5 GeV) and midrapidity (|y|<1.6), psi(2S) are found to be more suppressed in PbPb collision than J/psi. Also the nuclear modification factors of the three Y states are found to decrease with decreasing binding energy, as expected in a sequential melting scenario. Furthermore, the nuclear modification factor of non-prompt J/psi from b-hadron decays gives access to study the energy loss of b-quarks in the quark-gluon plasma.
Author
Torsten Dahms
(Ecole Polytechnique (FR))
