Measurement of quarkonium production at forward rapidity in ... formula ... collisions at ... formula ...TeV

摘要

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=7TeV 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: id="IEq21">σJ/ψ = 6.69 ± 0.04 ± 0.63  id="IEq22">μb, id="IEq23">σψ(2S) = 1.13 ± 0.07 ± 0.19  id="IEq24">μb, id="IEq25">σΥ(1S) = 54.2  ±  5.0 ± 6.7 nb and id="IEq26">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.