Charge Properties of theKMeson and Hyperon Decay Interaction

The question of the $\Delta T$ involved in strange-particle decays is discussed in terms of universal Fermi interactions. The fundamental interactions considered contain $\Delta T>\mathrm{}\frac{1}{2}$ as suggested by both experimental and purely theoretical considerations. It is found that by assuming global symmetry in both the pion coupling and the weak coupling one may restrict the $\Delta T$ to ½ in a class of processes involved in hyperon decay. These are the processes in which the real pion is given off externally. A symmetry may also be incorporated which forbids the decay ${\Xi }^{-}\to N+\pi$. A breakdown of this symmetry is necessary to allow ${\Sigma }^{-}$ decay. Reasons are developed for this breakdown to be manifested primarily in the $P$-wave part of $\Sigma$ and $\Lambda$ decay. A consequence is that ${\Sigma }^{-}$ decay should allow no parity nonconservation. The assumption of global symmetry enables one to connect $\Sigma$ decay to $\Lambda$ decay. Fitting the decay rates in the suggested model yields a prediction of the $\Lambda$ decay rate and asymmetry in agreement with experiment. Various ways of obtaining a selection rule prohibiting the ${\theta }^{+}$ mode of $K$ decay are discussed. These depend on symmetries which may be incorporated into an interaction containing $\Delta T=\frac{1}{2}, \frac{3}{2}, \mathrm{and} \frac{5}{2}$.