Photoproduction of Pion Pairs near Threshold

Abstract

The principal features of the reaction $\ensuremath{\gamma}+p\ensuremath{\rightarrow}p+{\ensuremath{\pi}}^{+}+{\ensuremath{\pi}}^{\ensuremath{-}}$ in the photon lab energy range 300 to 800 MeV are shown to be accounted for quantitatively by the interaction current. The dominant process is the production of the 3-3 isobar along with an $S$-wave pion.