Measurement of quarkonium production at forward rapidity in pp√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 p T and rapidity y, over the ranges 0<p T <20 GeV/c for J/ψ, 0<p T <12 GeV/c for all other resonances and for \(2.5) . The measured cross sections integrated over p T and y, and assuming unpolarized quarkonia, are: σ J/ψ =6.69±0.04±0.63 μ b, σ ψ(2S) =1.13±0.07±0.19 μ b, σ Υ(1S) =54.2±5.0±6.7 nb and σ Υ(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.