Heidelberg 2015 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 5: Heavy Ion Collisions and QCD Phases 1
HK 5.1: Gruppenbericht
Montag, 23. März 2015, 14:30–15:00, T/HS1
Measurement of the J/ψ production in pp, p–Pb and Pb–Pb collisions with ALICE at LHC — •Julian Book for the ALICE collaboration — Institut für Kernphysik, Goethe-Universität Frankfurt am Main
The investigation of the properties of strongly interacting matter under extreme conditions is the aim of the ALICE experiment. Quarkonia, i.e. bound states of heavy (charm or bottom) quarks such as the J/ψ, are expected to be produced in initial hard scattering processes in hadronic collisions. Thus they will provide insights into the earliest and hottest stages of nucleus-nucleus collisions where the formation of a Quark-Gluon Plasma is expected.
We present final results of J/ψ production in pp, p–Pb and Pb–Pb collisions performed by ALICE at the LHC in the first 4 years of data taking. Measurements in p–Pb and pp collisions help to decouple cold nuclear matter effects from hot nuclear effects in Pb-Pb collisions and serve as reference for the interpretation and evaluation of medium induced effects, such as color screening and recombination. Measurements differential in pT and centrality of J/ψ decaying into e+e− obtained at mid-rapidity (|y|<0.9) for the different collisions systems will be shown. Clearly less suppression with respect to SPS and RHIC results can be seen in Pb–Pb collisons at √sNN=2.76 TeV. Results for J/ψ decaying into µ+µ− measured at forward rapidities (2.5<y<4.0) will be presented. Furthermore, comparisons to theoretical calculations will be shown and their impact will be discussed.