Abstract
A measurement of J/ψ and ψ(2S) production is presented. It is based on a data sample from Pb+Pb collisions at √ sNN =5.02 TeV and pp collisions at √ s =5.02 TeV recorded by the ATLAS detector at the LHC in 2015, corresponding to an integrated luminosity of 0.42 nb−1 and 25 pb−1 in Pb+Pb and pp, respectively. The measurements of per-event yields, nuclear modification factors, and non-prompt fractions are performed in the dimuon decay channel for 9<pμμT<40 GeV in dimuon transverse momentum, and −2<yμμ<2 in rapidity. Strong suppression is found in Pb+Pb collisions for both prompt and non-prompt J/ψ , increasing with event centrality. The suppression of prompt ψ(2S) is observed to be stronger than that of J/ψ , while the suppression of non-prompt ψ(2S) is equal to that of the non-prompt J/ψ within uncertainties, consistent with the expectation that both arise from b-quarks propagating through the medium. Despite prompt and non-prompt J/ψ arising from different mechanisms, the dependence of their nuclear modification factors on centrality is found to be quite similar.
Original language | English |
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Article number | 762 |
Number of pages | 28 |
Journal | European Physical Journal C |
Volume | 78 |
Issue number | 9 |
DOIs | |
Publication status | Published - 21 Sept 2018 |
Bibliographical note
39 pages in total, author list starting page 23, 9 figures, 3 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2016-07Keywords
- nucl-ex
- hep-ex