Study of Λb0 and Ξb0 Decays to Λ h+ h′− and Evidence for CP Violation in Λb0 → Λ K+ K− Decays

A study of Λb0 and Ξb0 decays to Λ h+ h′− (h(′) = π, K) is performed using pp collision data collected by the LHCb experiment during LHC Runs 1−2, corresponding to an integrated luminosity of 9 fb^−1. The branching fractions for these decays are measured using the Λb0 → Λc+(→ Λ π+) π− decay as control channel. The decays Λb0 → Λ π+ π− and Ξb0 → Λ K− π+ are observed for the first time. For decay modes with sufficient signal yields, CP asymmetries are measured in the full and localized regions of the final-state phase space. Evidence is found for CP violation in the Λb0 → Λ K+ K− decay, interpreted as originating primarily from an asymmetric Λb0 → N*+ K− decay amplitude. The measured CP asymmetries for the other decays are compatible with zero.