Observation of the Λ_b⁰→Λ_c⁺K⁺K⁻π⁻ decay

The Λ_b⁰→Λ_c⁺K⁺K⁻π⁻ decay is observed for the first time using a data sample of proton-proton collisions at centre-of-mass energies of s=7 and 8TeV collected by the LHCb detector, corresponding to an integrated luminosity of 3fb⁻¹. The ratio of branching fractions between the Λ_b⁰→Λ_c⁺K⁺K⁻π⁻ and the Λ_b⁰→Λ_c⁺D_s⁻ decays is measured to be [Formula presented] where the first uncertainty is statistical, the second systematic and the third is due to the knowledge of the D_s⁻→K⁺K⁻π⁻ branching fraction. No structure on the invariant mass distribution of the Λ_c⁺K⁺ system is found, consistent with no open-charm pentaquark signature.