Abstract
Abstract The production of J/ψ and $ \varUpsilon $ mesons in pp collisions at $ \sqrt{s}=8 $ TeV is studied with the LHCb detector. The J/ψ and $ \varUpsilon $ mesons are reconstructed in the μ + μ − decay mode and the signal yields are determined with a fit to the μ + μ − invariant mass distributions. The analysis is performed in the rapidity range 2. 0 < y < 4. 5 and transverse momentum range 0 < p T < 14 (15) GeV/c of the J/ψ $ \left( \varUpsilon \right) $ mesons. The J/ψ and $ \varUpsilon $ production cross-sections and the fraction of J/ψ mesons from b-hadron decays are measured as a function of the meson p T and y.
Highlights
The LHCb detector and data setThe LHCb detector [25] is a single-arm forward spectrometer covering the pseudorapidity range 2 < η < 5, designed for the study of particles containing b or c quarks
Studies of the production of the J/ψ and Υ (1S), Υ (2S) and Υ (3S) mesons have been performed using pp collision data taken at
In this paper first measurements of quarkonium production at s = 8 TeV are reported under the assumption of zero polarisation, an assumption that is discussed in the paper
Summary
The LHCb detector [25] is a single-arm forward spectrometer covering the pseudorapidity range 2 < η < 5, designed for the study of particles containing b or c quarks. Taking period at s = 8 TeV in April 2012 During this period the average number of interactions per crossing varied. The Υ meson analysis is based on a data sample, corresponding to an integrated luminosity of about 51 pb−1 of pp interactions, collected with an average of 1.3 visible interactions per crossing. The analysis for the more abundant J/ψ mesons is based on data, corresponding to an integrated luminosity of about 18 pb−1, collected with an average of 1.0 visible interactions per crossing. In the subsequent software trigger, two well reconstructed tracks are required to have hits in the muon system, a pT higher than 500 MeV/c, p higher than 6 GeV/c and to form a common vertex. 120 MeV/c2 of the known J/ψ meson mass [28] or larger than 4.7 GeV/c2 are retained for further analysis
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