Analysis of nucleon form factor data reveals the $$e^ + e^ - \to n\bar n$$ cross-section to be remarkably larger than the $$e^ + e^ - \to p\bar p$$ oneone

Nucleon electromagnetic structure revisited

“…As a result, the following numerical values of the corresponding coupling constants are predicted f (1) ω N N = 18.9527; f (1) ρN N = 1.9335;…”

“…Most of the references concerning the nucleon space-like data can be found in [1]. More recent precise measurements are presented in [2][3][4][5][6][7][8][9][10].…”

“…The model gives large values of the f (1,2) φN N 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 s 0 = 9m 2 π are complex functions, the isoscalar spectral function behaviours are predicted as well.…”

“…A crucial factor in the latter achievement is the inclusion of a contribution of the fourth excited state of the ρ(770) meson with the parameters m ρ ′′′′ = 2455 ± 53M eV, Γ ρ ′′′′ = 728 ± 2M eV and (f (1) ρ ′′′′ N N /f ρ ′′′′ ) = 0.0549 ± 0.0005, (f (2) ρ ′′′′ N N /f ρ ′′′′ ) = −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 ρ(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.…”

Asymptotic conditions for the electromagnetic form factors of hadrons represented by the VMD model

“…In a construction of the unitary and analytic model [1][2][3][4][5][6] of the electromagnetic (EM) structure of an arbitrary hadron, the vector-meson-dominant (VMD) pole parametrization of EM form factors (FF's)…”