A Phenomenological Description of (\pi^{-}\Delta^{++}) Photo- and   Electroproduction in Nucleon Resonance Region
  The (\pi^{-}\Delta^{++}) production on the nucleon by real and virtual photons is discussed as initial step in a simple model approach for the two pion photo- and electroproduction on the nucleon, with emphasis on nucleon resonance excitation which is of interest for new facilities like TJNAF. A calculation for (\pi^{-}\Delta^{++}) channel in resonance excitation region is presented and compared to existing experimental data along with a discussion of physical effects that we find to be of relevance. The calculation is proposed as a starting basis for the investigation of (N^{*}) electromagnetic form factors using experimental data about two pion production by real and virtual photons. 
M. Ripani, V. Mokeev, M. Anghinolfi, M. Battaglieri, G. Fedotov, E.   Golovach, B.Ishkhanov, M. Osipenko, G. Ricco, V. Sapun...