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

Decays of Ξ _b ⁻ and Ω _b ⁻ baryons to Λ _c ⁺h ⁻h ^′− 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 s = 7, 8 and 13 TeV. The products of the relative branching fractions and fragmentation fractions for each signal mode, relative to the B ⁻→Λ _c ⁺p¯π ⁻ mode, are measured, with Ξ _b ⁻→Λ _c ⁺K ⁻π ⁻, Ξ _b ⁻→Λ _c ⁺K ⁻K ⁻ and Ω _b ⁻→Λ _c ⁺K ⁻K ⁻ decays being observed at over 5 σ significance. The Ξ _b ⁻→Λ _c ⁺K ⁻π ⁻ mode is also used to measure the Ξ _b ⁻ production asymmetry, which is found to be consistent with zero. In addition, the B ⁻→Λ _c ⁺p¯K ⁻ decay is observed for the first time, and its branching fraction is measured relative to that of the B ⁻→Λ _c ⁺p¯π ⁻ mode.