English

Nucleon electromagnetic form-factors in a minimal Gari-Krümpelmann model including the explicit two-pion continuum

Nuclear Theory 2026-08-11 v1 High Energy Physics - Experiment High Energy Physics - Phenomenology Nuclear Experiment

Abstract

The Gari--Kr\"umpelmann (GK) model provided one of the first semiphenomenological descriptions of the electromagnetic nucleon form-factors over a wide range of momentum transfer. It combined vector-meson dominance at low and intermediate momentum transfer with perturbative-QCD constraints at large momentum transfer. The present work extends this framework by including the dispersive two-pion continuum explicitly in the isovector channel. The two-pion contribution is taken from modern dispersive analyses and embedded into the intrinsic high-Q2Q^2 structure of the GK ansatz. The physical ρ\rho dynamics is then interpreted as part of the correlated two-pion spectral function. The direct coupling terms remain essential for the transition to the asymptotic regime. This gives a cleaner separation between long-range continuum dynamics, coherent vector-meson contributions, and direct quark-current dynamics. With just 5 parameters, we can describe the large body on form-factor data and differential cross sections from electron-proton scattering in the space-like region.

Keywords

Cite

@article{arxiv.2608.10907,
  title  = {Nucleon electromagnetic form-factors in a minimal Gari-Krümpelmann model including the explicit two-pion continuum},
  author = {Wulf Krümpelmann and Yong-Hui Lin and Ulf-G. Meißner},
  journal= {arXiv preprint arXiv:2608.10907},
  year   = {2026}
}

Comments

12 pages, 4 figures