Quarkonia and heavy-flavour production in CMS

Dahms, T. and Chatrchyan, S. and Khachatryan, V. and Sirunyan, A. M. and Tumasyan, A. and Adam, W. and Aguilo, E. and Bergauer, T. and Dragicevic, M. and Erö, J. and Fabjan, C. and Friedl, M. and Frühwirth, R. and Ghete, V. M. and Hammer, J. and Hörmann, N. and Hrubec, J. and Jeitler, M. and Kiesenhofer, W. and Knünz, V. and Krammer, M. and Krätschmer, I. and Liko, D. and Mikulec, I. and Pernicka, M. and Rahbaran, B. and Rohringer, C. and Rohringer, H. and Schöfbeck, R. and Strauss, J. and Bencze, György and Hajdu, Csaba and Hidas, Pál and Horváth, Dezső and Siklér, Ferenc and Veszprémi, Viktor and Vesztergombi, György and Molnár, József and Karancsi, János and Ujvári, Balázs and Veres, Gábor (2013) Quarkonia and heavy-flavour production in CMS. NUCLEAR PHYSICS A, 910-91. pp. 91-97. ISSN 0375-9474

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Abstract

The Compact Muon Solenoid (CMS) has measured numerous quarkonium states via their decays into μ+μ− pairs in pp and PbPb collisions at √sNN = 2.76 TeV. Quarko- nia are especially relevant for studying the quark-gluon plasma since they are pro- duced at early times and propagate through the medium, mapping its evolution. Non-prompt J/ψ from b-hadron decays show a strong suppression in the transverse momentum range (6.5 < pT < 30 GeV/c) when compared to the yield in pp collisions scaled by the number of inelastic nucleon-nucleon collisions. This suppression is re- lated to the in-medium b-quark energy loss. In the same kinematic region, for prompt J/ψ, a strong, centrality-dependent suppression is observed in PbPb collisions. Such strong suppression at high pT has previously not been observed at RHIC. At midra- pidity (|y| < 1.6) and the same pT region, inclusive ψ(2S) are even stronger sup- pressed than J/ψ, whereas ψ(2S) at forward rapidity (1.6 < |y| < 2.4) and lower pT (3 < pT < 30 GeV/c) appear to be less suppressed than J/ψ, however, with large uncer- tainties that prevent a conclusion. Furthermore, low-pT Υ(2S) and Υ(3S) mesons are strongly suppressed in PbPb collisions. The suppression of the Υ(1S) state is smaller than the suppression of the excited states and consistent with the suppression of the feed-down contribution only.

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