Study ofK−-Meson Decay Properties Using Dalitz Pairs forπ0Detection

A sample of about 5000 $K^{-}$ decays in flight, each accompanied by a Dalitz pair, has been observed in a hydrogen bubble chamber. These events consist of 3564 ± (3.1%) $K_{\pi 2}$ events, 786 ± (4.6%) $K_{e3\mathrm{}}$ events, 554 ± (7.6%) $K_{\mu 3}$ events, and 574 ± (5.9%) ${\tau }^{\prime }$ events. Ratios among these numbers give results in agreement with accepted $K^{+}$ branching ratios. The separation of the events has involved a sophisticated Monte Carlo program, ionization, kinematics of the $K^{-}$ decay, and kinematics of the Dalitz decay. The ${\pi }^{-}$ energy spectrum of the ${\tau }^{\prime }$ decays may be written as: $\left(\mathrm{phase}\mathrm{space}\right)\times [1+(\frac{2A}{{M_{\pi }}^2}\left)\right(s_3-s_0\left)\right]$, where $s_i$ is the square of the 4-momentum transfer to particle $i$, $s_0=\frac{1}{3}(s_1+s_2+s_3)$, and $A$ is a slope to be determined. We find $A=0.242\mathrm{}\pm 0.042$.