Prompt and Non-Prompt J/ ? and ?(2 S) Suppression at High Transverse Momentum in 5.02tev Pb+pb Collisions With the Atlas Experiment

Abstract

A measurement of J/ ? and ?(2 S) production is presented. It is based on a data sample from Pb+Pb collisions at sNN=5.02TeV and pp collisions at s=5.02TeV recorded by the ATLAS detector at the LHC in 2015, corresponding to an integrated luminosity of 0.42nb-1 and 25pb-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<pT??<40 GeV in dimuon transverse momentum, and - 2 < y? ?< 2 in rapidity. Strong suppression is found in Pb+Pb collisions for both prompt and non-prompt J/ ?, increasing with event centrality. The suppression of prompt ?(2 S) is observed to be stronger than that of J/ ?, while the suppression of non-prompt ?(2 S) is equal to that of the non-prompt J/ ? within uncertainties, consistent with the expectation that both arise from b-quarks propagating through the medium. Despite prompt and non-prompt J/ ? arising from different mechanisms, the dependence of their nuclear modification factors on centrality is found to be quite similar. © 2018, CERN for the benefit of the ATLAS collaboration.