Enhanced CP violation in D0→ρ0(ω)ρ0(ω)→π+π−π+π−

In the factorization approach we study the direct CP violation in D0→ρ0(ω)ρ0(ω)→π+π−π+π− (with unpolarized ρ0(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 Nc 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.