Measurement of ψ(2S) meson production in pp collisions at $\sqrt{s}=7\ \mbox{TeV}$

Abstract

The differential cross-section for the inclusive production of ψ(2S) mesons in pp collisions at has been measured with the LHCb detector. The data sample corresponds to an integrated luminosity of 36 pb−1. The ψ(2S) mesons are reconstructed in the decay channels ψ(2S)→μ+μ− and ψ(2S)→J/ψπ+π−, with the J/ψ meson decaying into two muons. Results are presented both for promptly produced ψ(2S) mesons and for those originating from b-hadron decays. In the kinematic range pT(ψ(2S))≤16 GeV/c and 2<y(ψ(2S))≤4.5 we measure where the last uncertainty on the prompt cross-section is due to the unknown ψ(2S) polarization. Recent QCD calculations are found to be in good agreement with our measurements. Combining the present result with the LHCb J/ψ measurements we determine the inclusive branching fraction where the last uncertainty is due to the , and branching fraction uncertainties.

Measurement of the relative yields of ψ(2S) to ψ(1S) mesons produced at forward and backward rapidity in Adare1, Aidala2, Ajitanand3 et al. 2017Phys. Rev. CSelf Cite

“…We see that at forward rapidity, the double ratio is consistent with unity in all three collision systems, indicating that any possible nuclear effects on the two charmonium states are comparable. Because these states are not fully formed until after they exit the nucleus, the fact that any nuclear effects have an equal magnitude Comparison of world data on the ratio of ψ(2S)/ψ(1S) mesons as a function of pT [29,40,[43][44][45], along with a calculation from a color evaporation model (CEM) at √ s=200 GeV [25].…”

Implications of LHCb measurements and future prospects

“…Traditionally, quarkonia production studies at hadron colliders have focussed on the study of J /ψ, ψ(2S) and Υ (nS) decays to dimuon or dielectron pairs [520]. The LHCb programme so far has followed this pattern with measurements of many cross-sections already published [521][522][523][524][525]. As an example of the quality of the data, Fig.…”

“…As the cross-sections for charmonium production at the LHC are large [521][522][523]525], the question of multiple production of these states in a single proton-proton collision naturally arises. Studies of double hidden charm and hidden and associated open charm production have been proposed as probes of the quarkonium production mechanism [526].…”

Measurements of the X c and X b Quarkonium States in pp Collisions with the ATLAS Experiment

“…The same predictions also provide a similarly good description of the prompt production of J/ψ and ψ(2S) [78,79,81].…”

“…The measurements of the prompt production cross-section of the χ c2 state, relative to the χ c1 state, shown in Figure 7.30, show that the χ c1 state is more readily produced than the χ c2 state within the region studied (accounting for their relative branching fractions, a factor of around 1. and ψ(2S) production at the LHC [77][78][79]81]. In the case of the J/ψ and ψ(2S), the appropriate inclusive branching fractions are available (i.e.…”