Direct CP violation in charmed hadron decays via ρ−ω mixing

Abstract

We study direct CP violation in the charmed hadron decays D+→ρ+ρ0(ω)→ρ+π+π−, D+→π+ρ0(ω)→π+π+π−, D0→φρ0(ω)→φπ+π−, D0→ηρ0(ω)→ηπ+π−, D0→η′ρ0(ω)→η′π+π−, D0→π0ρ0(ω)→π0π+π−, and Λc→pρ0(ω)→pπ+π− via ρ−ω mixing. The CP violation parameter depends on the effective parameter, Nc, which is relevant to hadronization dynamics of each decay channel. It is found that for fixed Nc the CP violation parameter reaches its maximum value when the invariant mass of the π+π− pair is in the vicinity of the ω resonance. For most of the parameter space explored the CP violating asymmetry is of order 10−4. However, over a small range, 1.98⩽Nc⩽1.99 and 1.95⩽Nc⩽2.02, the asymmetries for D0→π0ρ0(ω)→π0π+π− and Λc→pρ0(ω)→pπ+π− (respectively) can exceed 1%-at the cost of a small branching ratio, ∼2×10−8 and 7×10−9, respectively.