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    Measurement of nuclear modification factors of gamma(1S)), gamma(2S), and gamma(3S) mesons in PbPb collisions at root s(NN)=5.02 TeV

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    The cross sections for Ōí(1S), Ōí(2S), and Ōí(3S) production in lead-lead (PbPb) and proton-proton (pp) collisions at ‚ąösNN = 5.02 TeV have been measured using the CMS detector at the LHC. The nuclear modification factors, RAA, derived from the PbPb-to-pp ratio of yields for each state, are studied as functions of meson rapidity and transverse momentum, as well as PbPb collision centrality. The yields of all three states are found to be significantly suppressed, and compatible with a sequential ordering of the suppression, RAA(Ōí(1S)) > RAA(Ōí(2S)) > RAA(Ōí(3S)). The suppression of Ōí(1S) is larger than that seen at ‚ąösNN = 2.76 TeV, although the two are compatible within uncertainties. The upper limit on the RAA of Ōí(3S) integrated over pT, rapidity and centrality is 0.096 at 95% confidence level, which is the strongest suppression observed for a quarkonium state in heavy ion collisions to date. ¬© 2019 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP3.Peer reviewe

    Measurement of b jet shapes in proton-proton collisions at root s=5.02 TeV