Study of $b$-hadron decays to ${\Lambda }_c^{+}{h}^{-}{h}^{\mathrm{\prime }-}$ final states

Decays of ${\Xi }_b^{-}$ and ${\Omega }_b^{-}$ baryons to ${\Lambda }_c^{+}{h}^{-}{h}^{\mathrm{\prime }-}$ final states, with $h^{-}{h}^{\mathrm{\prime }-}$ being ${\pi }^{-}{\pi }^{-}$, $K^{-}{\pi }^{-}$ and $K^{-}{K}^{-}$ meson pairs, are searched for using data collected with the LHCb detector. The data sample studied corresponds to an integrated luminosity of $8.7{\mathrm{f}\mathrm{b}}^{-1}$ of $pp$ collisions collected at centre-of-mass energies $\sqrt{s}=7$, $8$ and $13\mathrm{T}\mathrm{e}\mathrm{V}$. The products of the relative branching fractions and fragmentation fractions for each signal mode, relative to the $B^{-}\to {\Lambda }_c^{+}\bar{p}{\pi }^{-}$ mode, are measured, with ${\Xi }_b^{-}\to {\Lambda }_c^{+}{K}^{-}{\pi }^{-}$, ${\Xi }_b^{-}\to {\Lambda }_c^{+}{K}^{-}{K}^{-}$ and ${\Omega }_b^{-}\to {\Lambda }_c^{+}{K}^{-}{K}^{-}$ decays being observed at over $5\sigma$ significance. The ${\Xi }_b^{-}\to {\Lambda }_c^{+}{K}^{-}{\pi }^{-}$ mode is also used to measure the ${\Xi }_b^{-}$ production asymmetry, which is found to be consistent with zero. In addition, the $B^{-}\to {\Lambda }_c^{+}\bar{p}{K}^{-}$ decay is observed for the first time, and its branching fraction is measured relative to that of the $B^{-}\to {\Lambda }_c^{+}\bar{p}{\pi }^{-}$ mode.