We answer the criticism that was raised against our Kemmer $K_{l3\mathrm{}}$ theory by exhibiting in explicit calculational detail the inequivalence of the Kemmer and Klein-Gordon formulations of $K_{l3\mathrm{}}$ decay, taking care to clearly define "inequivalence." It is shown that our published results are correct as stated, including the prediction of a zero in the scalar form factor.

• Received 22 October 1971

DOI:https://doi.org/10.1103/PhysRevD.6.726