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We present an overview of dynamic and related models for pion electroproduction on the nucleon due to Δ(1232) excitation. The electromagnetic multipoles and their ratios obtained from these models and from effective field theories are compared, and the existing contradictory results for the pion cloud effects are discussed.

We describe the application of a dispersion‐relation formalism to the virtual Compton scattering (VCS) reaction with the aim to extract information on generalized polarizabilities from VCS observables over a large energy range.

We report on our study of η photoproduction and electroproduction on the nucleon using an isobar model. The model contains nucleon Born terms and contributions from t-channel vector meson exchange as nonresonant background. In addition to the dominant S11(1535), we also include resonance contributions from D13(1520), S11(1650), D15(1675), F15(1680), D13(1700), P11(1710), and P13(1720). Within this model we analyze recent η photoproduction data for differential and total cross sections, beam and target asymmetries, as well as JLab electroproduction data. Good agreement has been achieved. With the new cross section data from GRAAL [2], we show that besides the dominant S11(1535), the second S11 resonance, S11(1650), is required in order to extract S11(1535) resonance parameters properly. In addition, the beam asymmetry data allow us to extract very small (