POLE DOMINANCE AND A LOW-ENERGY THEOREM IN RADIATIVE DECAYS OF CHARGED KAONS

A low-energy theorem is derived for the structure-dependent axial-vector form factor in the radiative decay K→l+ν+γ in the soft-kaon approximation. Corrections of the order of (mK2mV2) (V=ρ,ω,) are obtained in the pole-dominance approximation. In each approximation, the model predictions of both (i) asymptotic SU(3) and (ii) current mixing are investigated. The quantity aK(0)F(0) is calculated in both approximations and in both models. It is found that the soft-kaon result is shifted upward by approximately 20%; the separation between the models in the two approximations is of the same order of magnitude. © 1969 The American Physical Society.