Observation of ${\Xi }_b^0\to {\Xi }^{0}J/\psi$ and evidence for ${\Xi }_b^0\to {\Xi }^0\psi (2S)$ decays

Abstract

The first search for the beauty baryon decays ${\Xi }_b^0\to {\Xi }^{0}J/\psi$ and ${\Xi }_b^0\to {\Xi }^0\psi (2S)$ is presented using the proton-proton collision dataset collected by the LHCb experiment between 2016 and 2018, corresponding to an integrated luminosity of $5.4{\mathrm{fb}}^{-1}$. The first observation of the decay ${\Xi }_b^0\to {\Xi }^{0}J/\psi$ is reported and evidence of the decay ${\Xi }_b^0\to {\Xi }^0\psi (2S)$ is presented. The ${\Xi }^0$ hyperon is fully reconstructed for the first time at an LHC experiment, which is achieved using the ${\Xi }^0\to \Lambda {\pi }^0$ decay. The ratio of the branching fractions is measured as $\frac{\mathcal{B}({\Xi }_b^0\to {\Xi }^0\psi (2\mathcal{S}))}{\mathcal{B}({\Xi }_b^0\to {\Xi }^0\mathcal{J}/\psi )}=0.59\pm 0.19\text{(stat)}\pm 0.04\text{(syst)}$.

All figures and tables, along with any supplementary material and additional information, are available at https://lhcb-glance.cern.ch/alcm/public/analysis/full-details/6542/ (LHCb public pages)