Measurement of quarkonium production at forward rapidity in pp collisions at √s=7 TeV

Abstract

The inclusive production cross sections at forward rapidity of J/ψ, ψ(2S), Υ(1S) and Υ(2S) are measured in pp collisions at √s=7 TeV with the ALICE detector at the LHC. The analysis is based on a data sample corresponding to an integrated luminosity of 1.35 pb−1. Quarkonia are reconstructed in the dimuon-decay channel and the signal yields are evaluated by fitting the μ+μ− invariant mass distributions. The differential production cross sections are measured as a function of the transverse momentum pT and rapidity y, over the ranges 0<pT<20 GeV/c for J/ψ, 0<pT<12 GeV/c for all other resonances and for 2.5<y<4. The measured cross sections integrated over pT and y, and assuming unpolarized quarkonia, are: σJ/ψ=6.69±0.04±0.63 μb, σψ(2S)=1.13±0.07±0.19 μb, σΥ(1S)=54.2±5.0±6.7 nb and σΥ(2S)=18.4±3.7±2.9 nb, where the first uncertainty is statistical and the second one is systematic. The results are compared to measurements performed by other LHC experiments and to theoretical models.