# Study of $\chi_{b}$ meson production in pp collisions at $\sqrt{s}=7$ and 8TeV and observation of the decay $\chi_{b}(3P) \rightarrow \Upsilon(3S) \gamma$

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## Abstract

A study of $\chi_{b}$ 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 $\Upsilon(nS)$ mesons originating from $\chi_{b}$ decays is measured as a function of the $\Upsilon$ transverse momentum in the rapidity range $2.0 < y^{\Upsilon} < 4.5$. The radiative transition of the $\chi_{b}(3P)$ meson to $\Upsilon(3S)$ is observed for the first time. The $\chi_{b1}(3P)$ mass is determined to be $$m(\chi_{b1}(3P)) = 10 511.3 \pm 1.7 \pm 2.5 MeV/c^2,$$ where the first uncertainty is statistical and the second is systematic.

 Invariant mass distributions for selected dimuon candidates in the kinematic range $6 ## Tables and captions  Yields of$\Upsilon\mathrm{(nS)}$mesons, determined by fitting the dimuon invariant mass in the range$6

Created on 20 August 2019.Citation count from INSPIRE on 20 August 2019.