Measurement of Υ production in pp collisions at √s = 5 TeV

Abstract

The production cross-sections of Υ mesons, namely Υ(1S), Υ(2S) and Υ(3S), in pp collisions at √ s = 5 TeV are measured with a data sample corresponding to an integrated luminosity of 9.13 ± 0.18 pb−1 collected by the LHCb detector. The Υ mesons are reconstructed in the decay mode Υ → µ +µ −. Double differential cross-sections times branching fractions, as functions of the transverse momentum pT and the rapidity y of the Υ mesons, are measured in the range pT < 20 GeV/c and 2.0 < y < 4.5. The results integrated over these pT and y ranges are σ(Υ(1S)) × B(Υ(1S) → µ +µ −) = 2101 ± 33 ± 83 pb, σ(Υ(2S)) × B(Υ(2S) → µ +µ −) = 526 ± 20 ± 21 pb, σ(Υ(3S)) × B(Υ(3S) → µ +µ −) = 242 ± 16 ± 10 pb, where the first uncertainties are statistical and the second are systematic. The ratios of cross-sections between measurements of two different Υ states and between measurements at different centre-of-mass energies are determined. The nuclear modification factor of Υ(1S) at √ s = 5 TeV is updated as well using the directly measured cross-section results from this analysis.