Theory ofη−πMixing with Applications to Meson Decays

From a consideration of the intrinsic and radiative contributions to $\eta -\pi$ mixing, calculated in an effective-chiral-Lagrangian model, a satisfactory account is given of the process $\eta \to 3\pi$. The model lends itself to further application to the $G$-violating decay ${\rho }^{\pm }\to \eta {\pi }^{\pm }$, as well as to the weak processes $K^{\pm }\to {\pi }^{\pm }+{\pi }^0$ and $K^{\pm }\to {\pi }^{\pm }+\gamma +\gamma$. Also predicted are rates for $\varphi \to \eta +\gamma$ and $\omega \to \eta +\gamma$.