Pion radiative decay π → eνγ and anomalous weak currents

Pion radiative decay is an important testing ground for the properties of hadronic weak currents. We show that vector and axial vector form factors can be determined independently by measuring the circular polarization of the photon. A G-parity even axial current, if it couples in weak interactions, can contribute either constructively or destructively to the axial structure term in pion radiative decay. An estimate of this term is given, based on the commutators of weak currents of the first and second kind that we proposed previously. (orig.)