Coherent Production, Low-Energy Theorems, and Anomalous Ward Identities

Abstract

The significance of two low-energy theorems relating $\pi \to 2\gamma$, $\gamma \to 3\pi$, and $2\gamma \to 3\pi$ is stated. The processes ${\pi }^{\pm }+(Z, A)\to (Z, A)+{\pi }^{\pm }+{\pi }^0$, $e^{+}{e}^{-}\to e^{+}{e}^{-}3\pi$, and $e^{+}{e}^{-}\to 3\pi$ are discussed as experiments providing a check on these theorems. Some rate estimates are given.