Hadron States of Even Charge Conjugation from Electron-Positron Annihilation

We show how electron-positron storage rings may be used to obtain information on hadronic states with even charge conjugation. This is illustrated by studying the reaction $e^{-}{e}^{+}\to {\pi }^{-}{\pi }^{+}\gamma$, the analysis of which should reveal information on even-$C$ di-pion resonances, such as the existence of the $\epsilon$ meson.