New extraction of CP violation in b-baryon decays

Abstract

We study CP violation in b-baryon decays of Ξb−→Ξ−D with D=D0,D¯0 and Di(i=1,2). We find that these baryonic decay processes provide an ideal opportunity to measure the weak phase due to the absence of the relative strong phase. Explicitly, we relate ρ¯ and η¯ the CKM elements with the decay rate ratios of Ri=Γ(Ξb−→Ξ−Di)/Γ(Ξb−→Ξ−D0) without the charge conjugate states. As a complementary, we also examine the decay distributions of Λb→Λ(→pπ−)D. There are in total 32 decay observables, which can be parameterized by 9 real parameters, allowing the experiments to extract the angle γ≡arg⁡(−VudVub⁎/VcdVcb⁎) in the CKM unitarity triangle. In addition, the feasibilities of the experimental measurements are discussed. We find that ρ¯ and η¯ can be extracted at LHCb Run3 from Ξb−→Ξ−D, and a full analysis of Λb→Λ(→pπ−)D is available at LHCb Run4.