Overview of results on heavy flavour and quarkonia from the CMS collaboration

Abstract

The non-prompt J / ψ from B-meson decays, the prompt J / ψ , the inclusive ψ ′ and the three ϒ states were measured separately using the Compact Muon Solenoid (CMS) experimental apparatus in both pp and heavy-ion collisions at s N N = 2.76 TeV . The results are based on data collected in 2011 which correspond to an integrated luminosity of 150 μ b − 1 of PbPb and 231 nb − 1 of pp collisions. The yields measured in heavy-collisions are compared to those in pp scaled by the number of binary collisions via the nuclear modification factor, R A A . The high- p T prompt J / ψ show a suppression that does not vary with rapidity or p T . The R A A versus centrality calculated separately for ϒ ( 1 S ) and ϒ ( 2 S ) , shows less suppression for the ground state. An upper limit for ϒ ( 3 S ) was also calculated. Combining all the quarkonia states R A A measured by CMS, and considering the binding energy of each state, an ordering of the suppression is observed, which establishes, experimentally, the validity of the sequential melting scenario in heavy-ion collisions. The non-prompt J / ψ R A A dependence with p T and rapidity was measured in fine bins of centrality. These represent the first detailed measurements, in heavy-ion collision, of the b-quark energy loss kinematic dependence.