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

A measurement of   J/ψ  and   ψ(2S)  production is presented. It is based on a data sample from Pb+Pb collisions at   √ s_NN =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<p^μμ_T<40  GeV in dimuon transverse momentum, and   −2<y_μμ<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.