Observation of the $\hat{I}{›}_b^0\to J/\ddot{I}ˆ\hat{I}{ž}^{-}{K}^{+}$ and $\hat{I}{ž}_b^0\to J/\ddot{I}ˆ\hat{I}{ž}^{-}\ddot{I}{€}^{+}$ decays

Abstract

The first observation of the $\hat{I}{ž}_b^0\to J/\ddot{I}ˆ\hat{I}{ž}^{-}\ddot{I}{€}^{+}$ decay and the most precise measurement of the branching fraction of the $\hat{I}{›}_b^0\to J/\ddot{I}ˆ\hat{I}{ž}^{-}{K}^{+}$ decay are reported, using proton-proton collision data from the LHCb experiment collected in 2016--2018 at a centre-of-mass energy of 13~TeV, corresponding to an integrated luminosity of 5.4~fb${}^{-1}$. Using the $\hat{I}{›}_b^0\to J/\ddot{I}ˆ\hat{I}›$ and $\hat{I}{ž}_b^0\to J/\ddot{I}ˆ\hat{I}{ž}^{-}$ decays as normalisation channels, the ratios of branching fractions are measured to be: \[ \frac{\mathcal{B}(Λ_b^0 \to J/ψΞ^- K^+)}{\mathcal{B}(Λ_b^0 \to J/ψΛ)} = (1.17 \pm 0.14 \pm 0.08)\times 10^{-2} \, , \] \[ \frac{\mathcal{B}(Ξ_b^0 \to J/ψΞ^- π^+)}{\mathcal{B}(Ξ_b^0 \to J/ψΞ^-)} = (11.9 \pm 1.4 \pm 0.6)\times 10^{-2}\, , \] where the first uncertainty is statistical and the second systematic.

All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://lbfence.cern.ch/alcm/public/analysis/full-details/3479 (LHCb public pages)