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Abstract

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⁺pπ⁻ 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 5σ 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⁺pK⁻ decay is observed for the first time, and its branching fraction is measured relative to that of the B⁻ → Λ_c⁺pπ⁻ mode.