Enhanced direct CP violation in B±→ρ0π±

Abstract

We study direct CP violation in the hadronic decay B±→ρ0π±, including the effect of ρ-ω mixing. We find that the CP violating asymmetry is strongly dependent on the CKM matrix elements, especially the Wolfenstein parameter η. For fixed Nc (the effective parameter associated with factorization), the CP violating asymmetry a has a maximum of order 30%–50% when the invariant mass of the π+π- pair is in the vicinity of the ω resonance. The sensitivity of the asymmetry a to Nc is small. Moreover, if Nc is constrained using the latest experimental branching ratios from the CLEO Collaboration, we find that the sign of sin δ is always positive. Thus, a measurement of direct CP violation in B±→ρ0π± would remove the mod(π) ambiguity in arg[-[VtdVtb⋆/VudVub⋆].