New Determination of theK10Branching Ratio

Abstract

Using the 12-in. xenon bubble chamber, we have redetermined the branching ratio of the decay modes ${K_1}^0\to 2{\pi }^0$ and ${K_1}^0\to {\pi }^{+}+{\pi }^{-}$. Exposure of the chamber to an 800-MeV/c separated $K^{+}$ beam produced a large number of $K^0$ particles by charge exchange in the xenon, leading to about 3500 ${K_1}^0$ decays. The ${K_1}^0\to 2{\pi }^0$ decay mode is recognized by observation of the electron pairs formed by conversion of the $\gamma$ rays from ${\pi }^0$ decay. From an analysis of these data, we have determined the ${K_1}^0$ branching ratio to be $\frac{({K_1}^0\to 2{\pi }^0)}{\left[\right({K_1}^0\to 2{\pi }^0)+({K_1}^0\to {\pi }^{+}+{\pi }^{-}\left)\right]}=0.335\mathrm{}\pm 0.014$. This result is in very good agreement with the value of 0.337 predicted by the $\left|\Delta \mathrm{T}\right|=\frac{1}{2}$ rule.