Intermediate Vector Boson and Radiative Lepton Decay of theKMeson

$K$ meson decay into electron, neutrino, and photon is analyzed in the lowest order perturbation with respect to weak and electromagnetic interactions, but without making any approximation regarding the strong interaction. The weak interaction is assumed to be transmitted by a single charged intermediate vector meson, which interacts with the weak current in the conventional way. It is pointed out here that a certain angular and momentum distribution of decay particles could reveal almost unequivocally whether the intermediate vector meson does exist. It is shown also that other lepton decays of the $K$ meson, which includes $\mu$ mesons and $\pi$ mesons, cannot be used for the same purpose.