Some difficulties with the use of the Kemmer--Duffin formalism for pseudoscalar mesons

While the Kemmer-Duffin formalism for pseudoscalar mesons eliminates some difficulties in the analysis of $K_{l3}$ form factors, it gives rise to difficulties in other areas. It is shown that this formalism leads to: (i) a linear Gell-Mann---Okubo mass formula for mesons; (ii) an incompatibility between SU(3)-symmetric meson-nucleon couplings and experiment; (iii) (3*,3) breaking of chiral symmetry (H′=u⁰+cu⁸) leads to c=-0.9 and $\frac{f_K}{f_{\pi }}={\left(\frac{m_{\pi }}{m_K}\right)}^{\frac{1}{2}}$.