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HK: Fachverband Physik der Hadronen und Kerne
HK 29: Schwerionenkollisionen und QCD Phasen
HK 29.1: Gruppenbericht
Dienstag, 5. März 2013, 14:00–14:30, HSZ-201
J/ψ production in Pb–Pb collisions at √sNN = 2.76 TeV measured with ALICE at the LHC — •Jens Wiechula — Physikalisches Institut, Eberhard Karls Universität Tübingen
Charmonium production has been proposed as an important probe to study the phase of deconfined quarks and gluons (QGP) produced in ultra-relativistic heavy-ion collisions. Due to their large mass, charm quark production can only happen in the initial parton interactions, so that they participate in the whole collision evolution. More than 25 years ago it was predicted that J/ψ production, due to colour screening mechanisms in the QGP phase, should be suppressed in ultra-relativistic heavy-ion collisions in comparison to the yield in pp collisions scaled by the number of binary nucleon-nucleon interactions. This effect has indeed been observed, first at the SPS and later by the RHIC experiments. At LHC energies, however, the large abundance of produced charm quarks allows for studying other J/ψ production mechanisms via (re)combination of c and c quarks.
ALICE is the dedicated heavy-ion experiment at the LHC. J/ψ production is measured at mid- and forward rapidity in the di-electron and di-muon decay channel, respectively. In both rapidity intervals the acceptance reaches down to pT=0, being unique among the LHC experiments. Results on the nuclear modification factor (RAA) will be presented. A differential analysis as a function of transverse momentum, rapidity and collision centrality has been performed. The results will be discussed and compared to various theoretical calculations.