Direct CP violation in $\tau^\pm\rightarrow K^\pm \rho^0   (\omega)\nu_\tau \rightarrow K^\pm \pi^+\pi^-\nu_\tau $
  We study the direct CP violation in the $\tau^\pm\rightarrow K^\pm \rho^0 (\omega)\nu_\tau \rightarrow K^\pm \pi^+\pi^-\nu_\tau$ decay process in the Standard Model. An interesting mechanism involving the charge symmetry violating mixing between $\rho^0$ and $\omega$ is applied to enlarge the CP asymmetry. With this mechanism, the maximum differential and localized integrated CP asymmetries can reach $-(5.6^{+2.9}_{-1.7})\times10^{-12}$ and $6.3^{+2.4}_{-3.3}\times 10^{-11}$, respectively, which still leave plenty room for CP-violating New Physics to be discovered through this process. 
Chao Wang, Xin-Heng Guo, Ying Liu, Rui-Cheng Li
hep-ph