FORM FACTORS AND PHOTOPRODUCTION IN RHO+RHO' MODEL

The nucleon isovector form factor F1V(t) is described by two isovector resonances, the ρ and the ρ′. The effect of the ρ′ resonance on current-algebra sum rules and on the normalization of the pion form factor Fπ(t) is investigated. The widths Γ(ρ→2π) and Γ(ρ→2l) are determined within fairly narrow limits to be in excellent agreement with a recent analysis of the colliding-beam data. The pion form factor in the spacelike region is found to behave like t-1 at large t. Using the γ-ρ′ coupling determined by this analysis, a possible explanation is given for the apparent discrepancies reported recently in photoproduction experiments. A discussion of the u=0, πN superconvergence relations is given. A detailed account of the nucleon form factors GEp(t) and GEn(t) is presented. © 1969 The American Physical Society.