Comparison between γN→π and πN→ϱN in the resonance region up to s=1.75 GeV via the vector-dominance-model

We display the helicity amplitudes for the N_? system for each J^P state of the N_π system in the reaction Nπ→N?. These amplitudes are obtained from a K-matrix fit to amplitudes of the reaction Nπ→Nπ and Nπ→Nππ (via the isobar model). We then take either these amplitudes or the resonance couplings estimated from these amplitudes and compare them to the photoproduction amplitudes via the V.D.M. Two possible kinematics are considered for the N_? system below its threshold. These four methods give a range in which the V.D.M. can be accomodated even at this low energy.