1. L. Wolfenstein (private communication), who pointed out the possibility of apprcciable interference effects in the π+π-γ channel.
2. P. Franzini, L. Kirsch, P. Schmidt, J. Steinberger andR. J. L’lano:Phys. Rev.,140, B 127 (1965).
3. E. Bellotti, A. Pullia, M. Baldo-Ceolin, E. Calimani, S. Clampolillo, H. Huzita, F. Mattioli andA. Sconza;Nuovo Cimento,45 A, 737 (1966).
4. These are in fact the most general forms of the radiative matrix elements, ℳ e should therefore be understood as the difference between the total matrix element for the emission of “electric” photons and the inner bremsstrahlung contribution given in (1). ℳ m is the total matrix element for radiation of “magnetic” photons.
5. All unexplained notations follow that ofT. T. Wu andC. N. Yang:Phys. Rev. Lett.,13, 380 (1964).