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<40 GeV in dimuon transverse momentum, and −2<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.

Prompt and non-prompt J/ ψ and ψ(2 S) suppression at high transverse momentum in 5.02TeV Pb+Pb collisions with the ATLAS experiment

Farina E. M.;Fraternali M.;Introzzi G.;Livan M.;Negri A.;Rebuzzi D. M.;Rimoldi A.;Sottocornola S.;
2018-01-01

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<40 GeV in dimuon transverse momentum, and −2<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.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11571/1271246
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