KL0Three-Body Decays and the|ΔI|=12Rules

Abstract

The absolute decay rate of ${K_L}^0$ into three-body charged modes, ${\Gamma }_L\left(\mathrm{ch}\right)$, was measured in a spark-chamber-counter experiment. The result is ${\Gamma }_L\left(\mathrm{ch}\right)=(15.1\mathrm{}\pm 1.9)\times {10}^6$ ${\sec }^{-1\mathrm{}}$. The partial rates in ${K_L}^0$ decay are obtained from this value and previously measured branching ratios. The results are in agreement with values obtained by requiring internal consistency among all measured ${K_L}^0$ decay rates, absolute and relative. Comparison with the conjugate $K^{+}$ partial decay rates is in agreement with the predictions of the $\left|\Delta \mathrm{I}\right|=\frac{1}{2}$ rules for both leptonic and nonleptonic decays. As by-products of this investigation we have (a) measured the lifetime of ${K_S}^0$, (b) searched for coherent interference between ${K_L}^0$ and ${K_S}^0$ through their decays into two charged pions, and (c) verified the vector nature of the coupling in the leptonic decays of ${K_L}^0$.