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HK: Hadronen und Kerne
HK 26: Electromagnetic Probes IV, Electro-, Photoproduction
HK 26.1: Group Report
Tuesday, March 17, 1998, 14:00–14:30, B
Pion Electroproduction on the Nucleon — •S. Kamalov, D. Drechsel, O. Hanstein, and L. Tiator — Institut f"ur Kernphysik, Universit"at Mainz, Becherweg 45, D-55099 Mainz
A new operator for pion photo- and electroproduction has been developed for the application to the reactions on nuclei at equivalent photon energies up to 1 GeV. The model contains Born terms, vector mesons and nucleon resonances (P33(1232), P11(1440),D13(1520),S11(1535),F15(1680), and D33(1700)). The resonance contributions are included taking into account unitarity to provide the correct phases of the pion photoproduction multipoles. The Q2 dependence of the resonance electromagnetic vertices is described with appropriate form factors in the electromagnetic helicity amplitudes. Within this model we have obtained good agreement with experimental data for pion photo- and electroproduction on nucleon (for the differential cross sections and polarization observables). Furthermore we give predictions for future experiments on pion electroproduction to be performed at Mainz, Bonn and TJNAF.
In a first application to reactions on few-body systems we will present calculations for coherent photo- and electroproduction on the deuteron and 3He at threshold and in the resonance region. Possible effects of medium modification for the nucleon resonances will be discussed.