Nucleon electromagnetic structure revisited

Unitary and analytic ten-resonance model of the nucleon electromagnetic (e.m.) structure with canonical normalizations and QCD (up to the logarithmic correction) asymptotics is constructed on the four-sheeted Riemann surface, which provides a superposition of vector-meson pole and continuum contributions in a very natural way. As a result it describes simultaneously all existing experimental space-like and time-like data on the proton e.m. form factors (ff's) and on the neutron e.m. ff's as well. A crucial factor in the latter achievement is the inclusion of a contribution of the fourth excited state of the rho(770) meson with the parameters m_rho'''' = 2455 +/- 53 MeV, Gamma_rho'''' = 728 +/- 2 MeV and (f⁽¹⁾_rho''''NN/f_rho'''') = 0.0549 +/- 0.0005, (f⁽²⁾_rho''''NN/f_rho'''') = -0.0103 +/- 0.0001. The pronounced effect of the two-pion continuum on the isovector spectral functions demonstrating a strong enhancement of the left wing of the rho(770) resonance close to two-pion threshold, which was revealed by Höhler and Pietarinen by means of the nucleon ff unitarity condition more than a quarter of the century ago, is predicted by the model automatically. The model gives large values of the f^(1,2)_phiNN coupling constants, thus indicating the violation of the OZI rule. Since in the framework of the considered model isoscalar ff's above their lowest branch point t^s₀ = 9m²_pi are complex functions, the isoscalar spectral function behaviours are predicted as well.