Contribution to Kaon Decays of Direct Isospin-Violating Nonelectromagnetic Interactions

Abstract

We discuss the effect of an isospin-violating nonelectromagnetic term $U_3$ on $K\to 2\pi$ and $K\to 3\pi$ decays. With the coefficient of the term $U_3$ compatible with electromagnetic mass differences, the contribution is too small to explain the $\frac{(K^{+}\to {\pi }^{+}{\pi }^0)}{(K_1^0\to 2\pi )}$ decay ratio and the deviations from the $\left|\Delta I\right|=\frac{1}{2}$-rule prediction of slope parameters in $K\to 3\pi$ decays.