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

A study of Λ0 b and Ξ0 b decays to Λhþh0− (hð0Þ ¼ 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 Λ0 b → Λþ c ð→ ΛπþÞπ− decay as a control channel. The decays Λ0 b → Λπþπ− and Ξ0 b → ΛK−πþ 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 Λ0 b → ΛKþK− decay, interpreted as originating primarily from an asymmetric Λ0 b → NþK− decay amplitude. The measured CP asymmetries for other decays are compatible with zero.