Study of K--meson decay properties using Dalitz pairs for π0 detection

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%) Kₑ₃ events, 554 ± (7.6%) $K_{\mu 3}$ events, and 574 ± (5.9%) τ′ 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 π⁻ energy spectrum of the τ′ decays may be written as: $\left(phasespace\right)\times [1+(\frac{2A}{{M_{\pi }}^2}\left)\right(s_3-s_0\left)\right]$, where sᵢ is the square of the 4-momentum transfer to particle i, s₀=1/3(s₁+s₂+s₃), and A is a slope to be determined. We find A=0.242±0.042.