Non-Standard Model of the Nucleon Electromagnetic Structure and its Predictability

Abstract

Unitary and analytic ten-resonance model of the nucleon electromagnetic (e.m.) structure with canonical normalizations and asymptotics is constructed on a four-sheeted Riemann surface. It describes well all existing experimental space-like and time-like data on the nucleon e.m. form factors (ff's), including also FENICE (Frascati) results on the neutron, for the first time. This is achieved without any external constraints on the isovector spectral functions following from the piN-scattering data and pion e.m. ff behaviour through the unitarity condition. Just opposite, the model itself predicts a pronounced effect of the two-pion continuum on the isovector spectral functions revealing the strong enhancement of the left wing of the rho(770)-resonance close to two-pion threshold. The existence of the fourth excited state of the rho(770) meson with parameters mass and width equal to 2506 MeV and 700 MeV, respectively. The isoscalar spectral function behaviours are predicted by the presented model.