Study of b-hadron decays to Λc+h−h′− final states

Abstract

Decays of ${\mathrm{\Xi }}_b^{-}$ and ${\mathrm{\Omega }}_b^{-}$ baryons to ${\mathrm{\Lambda }}_c^{+}{h}^{-}{h}^{\prime -}$ final states, with h⁻h^′− being π⁻π⁻, K⁻π⁻ 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 fb⁻¹ of pp collisions collected at centre-of-mass energies $\sqrt{s}$ = 7, 8 and 13 TeV. The products of the relative branching fractions and fragmentation fractions for each signal mode, relative to the $B^{-}\to {\mathrm{\Lambda }}_c^{+}\overline{p}{\pi }^{-}$ mode, are measured, with ${\mathrm{\Xi }}_b^{-}\to {\mathrm{\Lambda }}_c^{+}{K}^{-}{\pi }^{-}$, ${\mathrm{\Xi }}_b^{-}\to {\mathrm{\Lambda }}_c^{+}{K}^{-}{K}^{-}$ and ${\Omega }_b^{-}\to {\mathrm{\Lambda }}_c^{+}{K}^{-}{K}^{-}$ decays being observed at over 5 σ significance. The ${\mathrm{\Xi }}_b^{-}\to {\mathrm{\Lambda }}_c^{+}{K}^{-}{\pi }^{-}$ mode is also used to measure the ${\mathrm{\Xi }}_b^{-}$ production asymmetry, which is found to be consistent with zero. In addition, the $B^{-}\to {\mathrm{\Lambda }}_c^{+}\overline{p}{K}^{-}$ decay is observed for the first time, and its branching fraction is measured relative to that of the $B^{-}\to {\mathrm{\Lambda }}_c^{+}\overline{p}{\pi }^{-}$ mode.