Form Factors of Kaon Semileptonic Decays

Abstract

A calculation of the semi--leptonic decays of the kaon ($K_{l3}$) is presented. The results are direct predictions of a covariant model of the pion and kaon introduced earlier by Ito, Buck, Gross. The weak form factors for $K_{l3}$ are predicted with absolutely no parameter adjustments of the model. We obtained for the form factor parameters: $f_-(q^2=m_l^2)/f_+(q^2=m_l^2)=-0.28$ and $\lambda_+$= 0.028, both within experimental error bars. Connections of this approach to heavy quark symmetry will also be discussed.