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

A study of Λb0 and Ξb0 decays to Λh+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+(→Λπ+)π- decay as a control channel. The decays Λb0→Λπ+π- and Ξb0→ΛK-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→ΛK+K- decay, interpreted as originating primarily from an asymmetric Λb0→N*+K- decay amplitude. The measured CP asymmetries for other decays are compatible with zero.