Direct CP Violation in Λ_b -> n (Λ)π^+π^- Decays via ρ-ωMixing

Abstract

We study direct CP violation in the bottom baryon decays Λ_b -> f ρ^0 (ω) -> fπ^+π^- (f=n or Λ). It is found that in these decays via ρ-ωmixing the CP violation could be very large when the invariant mass of the π^+π^- pair is in the vicinity of the ωresonance. With a typical value N_c =2 in the factorization approach, the maximum CP-violating asymmetries are more than 50% and 68% for Λ_b -> n π^+π^- and Λ_b -> Λπ^+π^-, respectively. With the aid of heavy quark symmetry and phenomenological models for the hadronic wave functions of Λ_b, Λand the neutron, we estimate the branching ratios of Λ_b -> n (Λ)ρ^0.

20 pages, 2 figires, Latex