Nucleon electromagnetic structure revisited

Abstract

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 $m_{{\rho }^{\prime \prime \prime \prime }}=2455\pm 53MeV,{\Gamma }_{{\rho }^{\prime \prime \prime \prime }}=728\pm 2MeV$ and $(f_{{\rho }^{\prime \prime \prime \prime }NN}^{(1)}/f_{{\rho }^{\prime \prime \prime \prime }})=0.0549\pm 0.0005$, $(f_{{\rho }^{\prime \prime \prime \prime }NN}^{(2)}/f_{{\rho }^{\prime \prime \prime \prime }})=-0.0103\pm 0.0001$. 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 $f_{\varphi NN}^{(1,2)}$ 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 $t_0^s=9m_{\pi }^2$ are complex functions, the isoscalar spectral function behaviours are predicted as well.

Latex, 29 pages, 6 eps figures

Cited by in corpus (23)

• Dispersion analysis of the nucleon form factors including meson continua
• Electromagnetic Form Factors of the Nucleon and Compton Scattering
• Inelastic Dark Matter at the LHC Lifetime Frontier: ATLAS, CMS, LHCb, CODEX-b, FASER, and MATHUSLA
• Nucleon Polarizabilities: from Compton Scattering to Hydrogen Atom
• Updated dispersion-theoretical analysis of the nucleon electromagnetic form factors
• Nucleon electromagnetic form factors and polarization observables in space-like and time-like regions
• Meson dominance of hadron form factors and large-Nc phenomenology
• On the pion cloud of the nucleon
• Once more on electromagnetic form factors of nucleons in extended vector meson dominance model
• Novel evaluation of the two-pion contribution to the nucleon isovector form factors
• Form factors and other measures of strangeness in the nucleon
• Searches for long-lived dark photons at proton accelerator experiments
• Unitary and analytic model of nucleon EM structure, the puzzle with JLab proton polarization data and new insight into proton charge distribution
• Nucleon Form Factors in Dispersion Theory
• Asymptotic behavior of nucleon electromagnetic form factors in time-like region
• Q^2-evolution of nucleon-to-resonance transition form factors in a QCD-inspired vector-meson-dominance model
• Pauli form factor contributions to the inelastic proton bremsstrahlung and dark photon production
• Duality, analyticity and t dependence of generalized parton distributions
• Phenomenological insight into JLab proton polarization data puzzle by deuteron impulse approximation
• Sum rule for a difference of proton and neutron total photoproduction cross-sections
• Flavor content of nucleon form factors in the space- and time-like region
• Prediction of neutron electromagnetic form factors behaviors just by the proton electromagnetic form factors data
• Manifestation of the JLab proton polarization data on the behaviour of strange nucleon form factors