Experimental Information on theπ±Photoproduction Amplitudes

Abstract

Recent data on ${\pi }^{\pm }$ photoproduction at 3.4 GeV are used to investigate the nature of the amplitudes contributing to these processes. It is found that a large amplitude corresponding to natural-parity $G=+1\mathrm{}$ exchange is necessary to explain the data, even in the region $t\approx -0.6\mathrm{}$ ${\mathrm{GeV}}^2$ where Reggeized $\rho$ exchange must vanish. This implies a large contribution from some ${\rho }^{\prime }$ trajectory or from cuts, absorption, etc. The large $G=+1\mathrm{}$ exchange amplitude needed to explain the $\frac{{\pi }^{-}}{{\pi }^{+}}$ ratio is only marginally consistent with the vector-dominance model.