Formula_17563

\[\begin{gathered}A\left(\mathrm{~K}_{S}^{0} \rightarrow \pi^{+} \pi^{-}\right)=\sqrt{2} f_{\pi} A\left(\mathrm{~K}_{L}^{0} \rightarrow \pi^{+} \pi^{-} \pi^{0}\right), \\q\left(\pi^{0}\right)=0,\end{gathered}\]