Dynamical coupled-channels analysis of ¹H(e,e^′π)N reactions

We have performed a dynamical coupled-channels analysis of available p(e,e^′π)N data in the region of W⩽1.6 GeV and Q²⩽1.45 (GeV/c)². The channels included are γ^*N, πN, ηN, and ππN that has πΔ, ρN, and σN components. With the hadronic parameters of the model determined in our previous investigations of πN→πN, ππN reactions, we have found that the available data in the considered W⩽1.6 GeV region can be fitted well by only adjusting the bare γ^*N→N^* helicity amplitudes for the lowest N^* states in P₃₃, P₁₁, S₁₁, and D₁₃ partial waves. The sensitivity of the resulting parameters to the amount of data included in the analysis is investigated. The importance of coupled-channels effect on the p(e,e^′π)N cross sections is demonstrated. The meson cloud effect, as required by the unitarity conditions, on the γ^*N→N^* form factors are also examined. Necessary future developments, both experimentally and theoretically, are discussed.