Inclusive quarkonium production in pp collisions at √s = 5.02 TeV

This article reports on the inclusive production cross section of several quarkonium states, J / ψ, ψ(2 S) , Υ (1 S) , Υ (2 S) , and Υ (3 S) , measured with the ALICE detector at the LHC, in pp collisions at s=5.02 TeV. The analysis is performed in the dimuon decay channel at forward rapidity (2.5 < y< 4). The integrated cross sections and transverse-momentum (p_T) and rapidity (y) differential cross sections for J / ψ, ψ(2 S) , Υ (1 S) , and the ψ(2 S) -to-J / ψ cross section ratios are presented. The integrated cross sections, assuming unpolarized quarkonia, are: σ_{J / ψ} (p_T< 20 GeV/c) = 5.88 ± 0.03 ± 0.34μb, σ_{ψ ( 2 S )} (p_T< 12 GeV/c) = 0.87 ± 0.06 ± 0.10μb, σ_{Υ ( 1 S )} (p_T< 15 GeV/c) = 45.5 ± 3.9 ± 3.5 nb, σ_{Υ (2 S)} (p_T< 15 GeV/c) = 22.4 ± 3.2 ± 2.7 nb, and σ_{Υ (3 S)} (p_T< 15 GeV/c) = 4.9 ± 2.2 ± 1.0 nb, where the first (second) uncertainty is the statistical (systematic) one. For the first time, the cross sections of the three Υ states, as well as the ψ(2 S) one as a function of p_Tand y, are measured at s=5.02 TeV at forward rapidity. These measurements also significantly extend the J / ψp_Treach and supersede previously published results. A comparison with ALICE measurements in pp collisions at s=2.76, 7, 8, and 13 TeV is presented and the energy dependence of quarkonium production cross sections is discussed. Finally, the results are compared with the predictions from several production models.