Alternate Modes of Decay of NeutralKMesons

Consideration is given to the possibility that the ${\theta }^0$ particle can decay via the "anomalous" modes ($e\pi \nu$) and ($\mu \pi \nu$). It is shown that, as a function of time, the decay rate for ${\theta }^0$ disintegration into a final state of this type, having definite signs of the charges, is the sum of three terms. Two of these are the expected exponentially decaying functions, characterized by the rates ${\lambda }_1$ and ${\lambda }_2$ for decay of the particles denoted as ${\theta }_1$ and ${\theta }_2$ by Gell-Mann and Pais. The third term is the product of an exponential having the decay rate $\frac{({\lambda }_1+{\lambda }_2)}{2}$ and an oscillating factor whose frequency depends on the difference in mass between the ${\theta }_1$ and ${\theta }_2$ particles. It arises from interference between ${\theta }_1$ and ${\theta }_2$ decay and has opposite signs for the ($e^{+}{\pi }^{-}\nu$) and ($e^{-}{\pi }^{+}\overline{\nu }$) modes. Similar effects occur for the muon decay modes. This interference may have the effect that the rate of disintegration into any one such final state increases with time during the early stages of decay. The detailed shape of the decay curve may be quite sensitive to the (${\theta }_1, {\theta }_2$) mass difference.