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

Abstract

This article reports on the inclusive production cross section of several quarkonium states, \(\textrm{J}/\psi \), \(\psi \mathrm{(2S)}\), \(\Upsilon \mathrm (1S)\), \(\Upsilon \mathrm{(2S)}\), and \(\Upsilon \mathrm{(3S)}\), measured with the ALICE detector at the LHC, in pp collisions at \(\sqrt{s} = 5.02\) TeV. The analysis is performed in the dimuon decay channel at forward rapidity (\(2.5< y < 4\)). The integrated cross sections and transverse-momentum (\(p_{\textrm{T}}\)) and rapidity (\(y\)) differential cross sections for \(\textrm{J}/\psi \), \(\psi \mathrm{(2S)}\), \(\Upsilon \mathrm (1S)\), and the \(\psi \mathrm{(2S)}\)-to-\(\textrm{J}/\psi \) cross section ratios are presented. The integrated cross sections, assuming unpolarized quarkonia, are: \(\sigma _{\textrm{J}/\psi }\) (\(p_{\textrm{T}} <20\) GeV/c) = 5.88 ± 0.03 ± 0.34\( ~\mu \)b, \(\sigma _{\psi \mathrm{(2S)}}\) (\(p_{\textrm{T}} <12\) GeV/c) = 0.87 ± 0.06 ± 0.10\(~\mu \)b, \(\sigma _{\Upsilon \mathrm (1S)}\) (\(p_{\textrm{T}} <15\) GeV/c) = 45.5 ± 3.9 ± 3.5 nb, \(\sigma _{\Upsilon \mathrm{(2S)}}\) (\(p_{\textrm{T}} <15\) GeV/c) = 22.4 ± 3.2 ± 2.7 nb, and \(\sigma _{\Upsilon \mathrm{(3S)}}\) (\(p_{\textrm{T}} <15\) 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 \(\Upsilon \) states, as well as the \(\psi \mathrm{(2S)}\) one as a function of \(p_{\textrm{T}}\) and \(y\), are measured at \(\sqrt{s} = 5.02\) TeV at forward rapidity. These measurements also significantly extend the \(\textrm{J}/\psi \) \(p_{\textrm{T}}\) reach and supersede previously published results. A comparison with ALICE measurements in pp collisions at \(\sqrt{s} = 2.76\), 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.