Measurement of theK10Charged-to-Neutral Decay Branching Ratio

Abstract

Using $K^0$ produced by $K^{+}$ charge exchange in Be, we have measured the charged-to-neutral branching ratio of $K_1^{}{}_{}{}^0$. We obtain 2.285 ± 0.055 to be compared with the $\left|\Delta I\right|=\frac{1}{2}$ rule prediction of 2.00. This 5-standard-deviation violation gives $\mathrm{Re}\left(\frac{A_2}{A_0}\right)cos({\delta }_2-{\delta }_0)=0.0345\mathrm{}\pm 0.007$.