Study of $χ_{b}$ meson production in pp collisions at $\sqrt{s}=7$ and 8TeV and observation of the decay $χ_{b}\rightarrow Υ(3S) γ$

Abstract

A study of $χ_{b}$ meson production at LHCb is performed on proton-proton collision data, corresponding to 3.0fb$^{-1}$ of integrated luminosity collected at centre-of-mass energies $\sqrt{s}=7$ and 8TeV. The fraction of $Υ(nS)$ mesons originating from $χ_{b}$ decays is measured as a function of the $Υ$ transverse momentum in the rapidity range $2.0 < y^Υ < 4.5$. The radiative transition of the $χ_{b}(3P)$ meson to $Υ(3S)$ is observed for the first time. The $χ_{b1}(3P)$ mass is determined to be $$m(χ_{b1}(3P)) = 10\,511.3 \pm 1.7 \pm 2.5 MeV/c^2,$$ where the first uncertainty is statistical and the second is systematic.

22 pages, 3 fugurs