Three-Body Leptonic Decays of theKMesons

A treatment is given of the three-body leptonic decays of the $K$ mesons on the basis of a phenomenological strangeness-changing weak-interaction Hamiltonian and an analysis is presented of the relevant decay form factors in terms of simple assumptions regarding the groups of eigenstates which are strongly coupled to the $K\pi$ system. The possibility of a violation of time-reversal invariance arising from the "out of phaseness" of the strangeness-changing $\Delta T=\frac{3}{2}$ and $\Delta T=\frac{1}{2}$ currents in $H_{\mathrm{weak}}$ is considered. Throughout the discussion, the available experimental data are used to extract as much information as possible about the parameters which are important theoretically.