Electromagnetic Form Factors of the Nucleon in Chiral Soliton Models
Abstract
Description
The ratio of electric to magnetic proton form factors G_E/G_M as measured in polarization transfer experiments shows a characteristic linear decrease with increasing momentum transfer Q^2. We present a simple argument how such a decrease arises naturally in chiral soliton models. For a detailed comparison of model results with experimentally determined form factors it is necessary to employ a boost from the soliton rest frame to the Breit frame. To enforce asymptotic counting rules for form factors, the model must be supplemented by suitably chosen interpolating powers n in the boost prescription. Within the minimal pi-rho-omega soliton model, with the same n for both, electric and magnetic form factors, it is possible to obtain a very satisfactory fit to all available proton data for the magnetic form factor and to the recent polarization results for the ratio G_E/G_M. At the same time the small and very sensitive neutron electric form factor is reasonably well reproduced. The results show a systematic discrepancy with presently available data for the neutron magnetic form factor G_M^n for Q^2 > 1 (GeV/c)^2. We additionally comment on the possibility to extract information about the form factors in the time-like region and on two-photon exchange contributions to unpolarized elastic scattering which specifically arise in soliton models.
Contribution to the volume "The Multifaceted Skyrmion" edited by G.E.Brown and Mannque Rho, publ.by World Scientific Publ. Comp., 2009. It is an updated and extended version of a talk originally presented at the workshop Nucleon05 "Nucleon Form Factors", Frascati, Oct. 12-14, 2005
Contribution to the volume "The Multifaceted Skyrmion" edited by G.E.Brown and Mannque Rho, publ.by World Scientific Publ. Comp., 2009. It is an updated and extended version of a talk originally presented at the workshop Nucleon05 "Nucleon Form Factors", Frascati, Oct. 12-14, 2005