Observation of the ${\Xi }_{\mathrm{b}}^{-}$ $\to$ $\psi$(2S)${\Xi }^{-}$ decay and studies of the ${\Xi }_{\mathrm{b}}$(5945)${}^0$ baryon in proton-proton collisions at $\sqrt{s}$ = 13 TeV

Abstract

The first observation of the decay ${\Xi }_{\mathrm{b}}^{-}$ $\to$ $\psi$(2S)${\Xi }^{-}$ and measurement of the branching ratio of ${\Xi }_{\mathrm{b}}^{-}$ $\to$ $\psi$(2S)${\Xi }^{-}$ to ${\Xi }_{\mathrm{b}}^{-}$ $\to$ J/$\psi$${\Xi }^{-}$ are presented. The J/$\psi$ and $\psi$(2S) mesons are reconstructed using their dimuon decay modes. The results are based on proton-proton colliding beam data from the LHC collected by the CMS experiment at $\sqrt{s}$ = 13 TeV in 2016-2018, corresponding to an integrated luminosity of 140 fb${}^{-1}$. The branching fraction ratio is measured to be $\mathcal{B}$(${\Xi }_{\mathrm{b}}^{-}$ $\to$ $\psi$(2S)${\Xi }^{-}$) / $\mathcal{B}$(${\Xi }_{\mathrm{b}}^{-}$ $\to$ J/$\psi$${\Xi }^{-}$) = 0.84 ${}_{-0.19}^{+0.21}$ (stat) $\pm$ 0.10 (syst) $\pm$ 0.02 ($\mathcal{B}$), where the last uncertainty comes from the uncertainties in the branching fractions of the charmonium states. New measurements of the ${\Xi }_{\mathrm{b}}$(5945)${}^0$ baryon mass and natural width are also presented, using the ${\Xi }_{\mathrm{b}}^{-}{\pi }^{+}$ final state, where the ${\Xi }_{\mathrm{b}}^{-}$ baryon is reconstructed through the decays J/$\psi {\Xi }^{-}$, $\psi$(2S)${\Xi }^{-}$, J/$\psi \Lambda$K${}^{-}$, and J/$\psi {\Sigma }^0$K${}^{-}$. Finally, the fraction of the ${\Xi }_{\mathrm{b}}^{-}$ baryons produced from ${\Xi }_{\mathrm{b}}$(5945)${}^0$ decays is determined.

arXiv commentCorrected the meta title and abstract to match the published version. All the figures and tables, including additional supplementary figures, can be found at http://cms-results.web.cern.ch/cms-results/public-results/publications/BPH-23-002 (CMS Public Pages)

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