Study of χb meson production in p p collisions at s√=7 and 8TeV and observation of the decay χb(3P)→Υ(3S)γ

A study of χb meson production at LHCb is performed on proton–proton collision data, corresponding to 3.0 fb−1of integrated luminosity collected at centre-of-mass energies s√ = 7 and 8 TeV. The fraction of Υ(nS) mesons originating from χb decays is measured as a function of the Υ transverse momentum in the rapidity range 2.0meson to Υ(3S) is observed for the first time. The χb1(3P) mass is determined to be mχb1(3P)=10511.3±1.7±2.5MeV/c2,where the first uncertainty is statistical and the second is systematic.