Abstract
The modification of the production of J/psi , psi (2mathrm {S}), and varUpsilon (nmathrm {S}) (n = 1, 2, 3) in p+Pb collisions with respect to their production in pp collisions has been studied. The p+Pb and pp datasets used in this paper correspond to integrated luminosities of 28~mathrm {nb}^{-1} and 25~mathrm {pb}^{-1} respectively, collected in 2013 and 2015 by the ATLAS detector at the LHC, both at a centre-of-mass energy per nucleon pair of 5.02 TeV. The quarkonium states are reconstructed in the dimuon decay channel. The yields of J/psi and psi (mathrm {2S}) are separated into prompt and non-prompt sources. The measured quarkonium differential cross sections are presented as a function of rapidity and transverse momentum, as is the nuclear modification factor, R_{pmathrm {Pb}} for J/psi and varUpsilon (nmathrm {S}). No significant modification of the J/psi production is observed while varUpsilon (nmathrm {S}) production is found to be suppressed at low transverse momentum in p+Pb collisions relative to pp collisions. The production of excited charmonium and bottomonium states is found to be suppressed relative to that of the ground states in central p+Pb collisions.
Highlights
The study of heavy quarkonium bound states in ultra-relativistic heavy-ion collisions [1,2] has been a subject of intense theoretical and experimental efforts since it was initially proposed by Matsui and Satz [3] as a probe to study a deconfined quark–gluon plasma (QGP) created in nucleus– nucleus (A+A) collisions
In proton–lead ( p+Pb) collisions, the modification of quarkonium production with respect to that in pp collisions may be quantified by the nuclear modification factor, RpPb, which is defined as the ratio of the quarkonium production cross section in p+Pb collisions to the cross section measured in pp collisions at the same centre-of-mass energy, scaled by the number of nucleons in the lead nucleus: R pPb
The double-differential production cross sections of five quarkonium states, J/ψ, ψ(2S), Υ (n = 1, 2, 3) are measured using using p+Pb collision data corresponding to an integrated luminosity of 28 nb−1 (25 pb−1) at a centre-of-mass energy per nucleon pair of 5.02 TeV collected by the ATLAS experiment at the LHC
Summary
The study of heavy quarkonium bound states (ccand bb) in ultra-relativistic heavy-ion collisions [1,2] has been a subject of intense theoretical and experimental efforts since it was initially proposed by Matsui and Satz [3] as a probe to study a deconfined quark–gluon plasma (QGP) created in nucleus– nucleus (A+A) collisions. Measurements of the J/ψ nuclear modification factor and forward ( p beam direction) to backward (Pb beam direction) cross-section ratio by the ALICE [19,20] and LHCb [21] experiments show strong suppression at large rapidity and low transverse momentum. The initialstate effects are expected to be largely cancelled out in double ratio due to the same modifications affecting partons before the formation of the quarkonium state, so measuring the relative suppression of different quarkonium states should help in understanding the properties of the final-state effects separately from the initial ones. The PHENIX experiment at RHIC has presented measurements of ψ(2S) suppression at mid-rapidity for d+Au interactions at √s = 200 GeV, showing that the charmonium double ratio is smaller than unity, and decreases from peripheral to central collisions [24]. The fourth is the charmonium and bottomonium double ratios, ρOpP(nbS)/O(1S), presented as a function of centre-of-mass rapidity and centrality
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
