On-shell current algebra and the radiative leptonic decays of pions and kaons

Abstract

The hard meson method of Schnitzer and Weinberg is used to study the radiative 1eptonic decays of π and K. The original formalism for SU(2) is generalized to include the case of strangeness changing axial vector currents and the isosca1ar part of the electromagnetic current. This method and dispersion relations are used to determine the form factors for the decays. It is shown that in the pole dominance approximation the relevant form factor in the axial vector amplitude cannot be unsubtracted. Possible alterations of our results arising from relaxing a smoothness approximation are estimated to be small.

We discuss several symmetry breaking schemes for the evaluation of necessary coupling constants. The branching ratio for K+ →ɤ e ʋ is calculated to be ~ 2 x 10-5 for interesting structure dependent decays. We finally investigate possible effects of e1ectromaghetic violations of time reversal invariance in the decay.