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HK: Physik der Hadronen und Kerne

HK 2: Theory I

HK 2.4: Talk

Monday, March 11, 2002, 17:45–18:00, A

Electromagnetic transition form factors and dilepton decay rates of nucleon resonances — •Mikhail Krivoruchenko, Christian Fuchs, Boris Martemyanov, and Amand Faessler — Institut fuer Theoretische Physik, Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen, Germany

Relativistic, kinematically complete phenomenological expressions for the dilepton decay rates of nucleon resonances with arbitrary spin and parity are derived in terms of the magnetic, electric, and Coulomb transition form factors. The dilepton decay rates of the nucleon resonances with masses below 2 GeV are estimated using the extended vector meson dominance model for the transition form factors. The model provides a unified description of the photo- and electroproduction data, the vector meson decays, and the dilepton decays. The constraints on the transition form factors from the quark counting rules are taken into account. The parameters of the model are fixed by fitting the available photo- and electroproduction data and using results of the multichannel partial-wave analysis of the π N scattering. The vector meson coupling constants of the magnetic, electric, and Coulomb types are determined. The dilepton widths and the dilepton spectra from decays of nucleon resonances with masses below 2 GeV are calculated [1,2]. The results are used to model the dilepton spectra in proton-proton, proton-deuteron, and heavy-ion collisions.

[1] M.I. Krivoruchenko, Amand Faessler: Phys.Rev. D 65, 017502 (2002). [2] M.I. Krivoruchenko, B.V. Martemyanov, Amand Faessler, C. Fuchs: submitted to Ann.Phys. (N.Y.), nucl-th/0110066.