Decay Properties of theωMeson

Abstract

The reaction $K^{-}p\to \Lambda \omega$, as observed in the Lawrence Radiation Laboratory's 72-in. hydrogen bubble chamber, has provided over 4600 examples of $\omega$ decay. The distribution of pion momenta in the decay $\omega \to {\pi }^{+}{\pi }^{-}{\pi }^0$, of which 4200 examples have been seen, is found to be consistent with $C$ conservation. With the assumption that the $\omega$ spin is $1^{-}$, the pion-momentum distributions predicted by two different decay matrix elements are compared with the experimental distributions, as a test for final-state interactions. It is also shown that a spin of $3^{-}$ for the $\omega$ is unlikely. Branching fractions of other decay modes with respect to the ${\pi }^{+}{\pi }^{-}{\pi }^0$ decay mode are: neutrals, 0.097±0.016; $\eta \gamma$, 0.017; $\eta {\pi }^0$, 0.017; ${\pi }^{+}{\pi }^{-}\gamma$, 0.05; $e^{+}{e}^{-}$, 0.0003; and ${\mu }^{+}{\mu }^{-}$, 0.0017. The $\omega \to {\pi }^{+}{\pi }^{-}$ branching fraction lies between ${(0.17\mathrm{}\pm 0.03)}^2$=0.029 (coherence between the $\rho$ and the $\omega$ production amplitudes assumed) and 0.082±0.020 (incoherence assumed).