Study of $\Upsilon$ production in $p$Pb collisions at $\sqrt{s_{NN}}=8.16$ TeV

Peter Clarke, Greig Cowan, Stephan Eisenhardt, Silvia Gambetta, Franz Muheim, Matthew Needham, Marco Pappagallo, Stephen Playfer, Mark Williams, LHCb Collaboration

Research output: Contribution to journalArticlepeer-review


The production of ϒ(nS) mesons (n = 1, 2, 3) in pPb and Pbp collisions at a centre-of-mass energy per nucleon pair $ \sqrt{s_{\mathrm{NN}}}=8.16 $ TeV is measured by the LHCb experiment, using a data sample corresponding to an integrated luminosity of 31.8 nb$^{−1}$. The ϒ(nS) mesons are reconstructed through their decays into two opposite-sign muons. The measurements comprise the differential production cross-sections of the ϒ(1S) and ϒ(2S) states, their forward-to-backward ratios and nuclear modification factors. The measurements are performed as a function of the transverse momentum p$_{T}$ and rapidity in the nucleon-nucleon centre-of-mass frame y$^{*}$ of the ϒ(nS) states, in the kinematic range p$_{T}$ < 25 GeV/c and 1.5 < y$^{*}$ < 4.0 (−5.0 < y$^{*}$ < −2.5) for pPb (Pbp) collisions. In addition, production cross-sections for ϒ(3S) are measured integrated over phase space and the production ratios between all three ϒ(nS) states are determined. Suppression for bottomonium in proton-lead collisions is observed, which is particularly visible in the ratios. The results are compared to theoretical models.
Original languageEnglish
Article number194
Journal Journal of High Energy Physics
Early online date29 Nov 2018
Publication statusE-pub ahead of print - 29 Nov 2018


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