Measurement of Upsilon production in collisions at root s=2.76 TeV

Abstract

The production of Υ(1S), Υ(2S) and Υ(3S) mesons decaying into the dimuon final state is studied with the LHCb detector using a data sample corresponding to an integrated luminosity of 3.3 pb−1 collected in proton-proton collisions at a centreof-mass energy of √ s = 2.76 TeV. The differential production cross-sections times dimuon branching fractions are measured as functions of the Υ transverse momentum and rapidity, over the ranges pT < 15 GeV/c and 2.0 < y < 4.5. The total crosssections in this kinematic region, assuming unpolarised production, are measured to be σ (pp → Υ(1S)X) × B Υ(1S)→ µ +µ − = 1.111 ± 0.043 ± 0.044 nb, σ (pp → Υ(2S)X) × B Υ(2S)→ µ +µ − = 0.264 ± 0.023 ± 0.011 nb, σ (pp → Υ(3S)X) × B Υ(3S)→ µ +µ − = 0.159 ± 0.020 ± 0.007 nb, where the first uncertainty is statistical and the second systemat