Measurement of ϒ production in pp collisions at s−−√=7 TeV

Abstract

The production of ϒ(1S), ϒ(2S) and ϒ(3S) mesons in proton-proton collisions at the centre-of-mass energy of s√=7 TeV

is studied with the LHCb detector. The analysis is based on a data sample of 25 pb−1 collected at the Large Hadron Collider. The ϒ mesons are reconstructed in the decay mode ϒ→μ + μ − and the signal yields are extracted from a fit to the μ + μ − invariant mass distributions. The differential production cross-sections times dimuon branching fractions are measured as a function of the ϒ transverse momentum p T and rapidity y, over the range p T <15 GeV/c and 2.0<y<4.5. The cross-sections times branching fractions, integrated over these kinematic ranges, are measured to be

where the first uncertainty is statistical, the second systematic and the third is due to the unknown polarisation of the three ϒ states.