Eur. Phys. J. C (2013) 73: 2519
https://doi.org/10.1140/epjc/s10052-013-2519-2

Regular Article - Theoretical Physics

Enhanced CP violation in D ⁰→ρ ⁰(ω)ρ ⁰(ω)→π ⁺ π ⁻ π ⁺ π ⁻

¹ College of Science, Henan University of Technology, Zhengzhou, 450001, China
² School of Nuclear Science and Technology, University of South China, Hengyang, Hunan, 421001, China
³ College of Nuclear Science and Technology, Beijing Normal University, Beijing, 100875, China

^* e-mail: xhguo@bnu.edu.cn

Received: 29 January 2013
Revised: 29 June 2013
Published online: 21 August 2013

Abstract

In the factorization approach we study the direct CP violation in D ⁰→ρ ⁰(ω)ρ ⁰(ω)→π ⁺ π ⁻ π ⁺ π ⁻ (with unpolarized ρ ⁰(ω)) via the ρ−ω mixing mechanism. We find that the CP violation can be enhanced due to a large strong phase difference when the masses of the π ⁺ π ⁻ pairs are in the vicinity of the ω resonance. The CP violation parameter depends on the effective parameter N _c which includes nonfactorizable effects and is determined by the experimental data. Taking into account double ρ−ω mixing contributions, we find the CP violating asymmetry is larger than these in the cases where no ρ−ω mixing or single ρ−ω mixing is taken into account. We also discuss the possibility to observe the predicted CP violation at BEPCII.