Radiative Pion Decay into Electrons

The possibility of distinguishing the pion structure-dependent radiation from the conventional inner bremsstrahlung radiation in the radiative decay of pions into electrons is discussed. Calculation of the photon energy spectrum and angular correlation shows that evidence for pion structure would be obtained if any photons of energy less that 70 Mev were detected in 180° coincidence with $\pi$-decay electrons. The probability of such events per unit solid angle is ≳0.2×${10}^{-7\mathrm{}}$ relative to ordinary $\pi \to \mu +\nu$ decay, if the assumption of a conserved vector current is made to relate the rate of radiative decay through the weak $V$-interaction to the rate of ${\pi }^0\to 2\gamma$ decay.