The Role of Mesons in the Electromagnetic Form Factors of the Nucleon

Abstract

The roles played by mesons in the electromagnetic form factors of the nucleon are explored using as a basis a model containing vector mesons with coupling to the continuum together with the asymptotic $Q^2$ behavior of perturbative QCD. Specifically, the vector dominance model (GKex) developed by Lomon is employed, as it is known to be very successful in representing the existing high-quality data published to date. An analysis is made of the experimental uncertainties present when the differences between the GKex model and the data are expanded in orthonormal basis functions. A main motivation for the present study is to provide insight into how the various ingredients in this model yield the measured behavior, including discussions of when dipole form factors are to be expected or not, of which mesons are the major contributors, for instance, at low-$Q^2$ or large distances, and of what effects are predicted from coupling to the continuum. Such insights are first discussed in momentum space, followed by an analysis of how different and potentially useful information emerges when both the experimental and theoretical electric form factors are Fourier transformed to coordinate space. While these Fourier transforms should not be interpreted as "charge distributions", nevertheless the roles played by the various mesons, especially which are dominant at large or small distance scales, can be explored via such experiment--theory comparisons.

Resubmitted to PRC

References in corpus (12)

• Recoil Polarization Measurements of the Proton Electromagnetic Form Factor Ratio to Q^2 = 8.5 GeV^2
• Dispersion analysis of the nucleon form factors including meson continua
• Two-Photon Physics in Hadronic Processes
• Measurement of the proton electric to magnetic form factor ratio from \vec ^1H(\vec e, e'p)
• The Charge Form Factor of the Neutron at Low Momentum Transfer from the ${}^2\vec{\mathrm{H}}(\vec{\mathrm{e}},{\mathrm{e}}^{\prime }\mathrm{n})\mathrm{p}$ Reaction
• Extraction of the Neutron Magnetic Form Factor from Quasi-Elastic 3He(pol)(e(pol),e') at Q^2 = 0.1 - 0.6 (GeV/c)^2
• Electroweak structure of the nucleon, meson cloud and light-cone wavefunctions
• Two-photon exchange at low Q^2
• Proton Electromagnetic Form Factor Ratios at Low Q^2
• The neutron negative central charge density: an inclusive-exclusive connection
• Generalized parton distributions in a meson cloud model
• Connecting the Breit Frame to the Infinite Momentum Light Front Frame: How G_E turns into F_1

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