New Possibilities for Studying Nucleon Resonances on the Basis of an Analysis of Polarization Observables and Off-Scattering-Plane Angular Distributions in the Reaction gammav p → pi+ pi- p

A model for describing the double charged-pion production by real and virtual photons in the energy region of nucleon-resonance excitation is further developed for calculating the angular distributions of reaction products off the scattering plane and the beam asymmetry. It is shown that investigation of these observables has a rich potential for extracting the first data on the Coulomb excitation of many nucleon resonances and for separating the contributions of various helicity amplitudes to the excitation of nucleon resonances by transverse photons