Eur. Phys. J. A (2004) 20: 469-473
https://doi.org/10.1140/epja/i2003-10223-y

Updated dispersion-theoretical analysis of the nucleon electromagnetic form factors

¹ Helmholtz-Institut für Strahlen- und Kernhysik (Theorie), Universität Bonn, 53115, Bonn, Germany
² Institut für Kernphysik (Theorie), Forschungszentrum Jülich, 52425, Jülich, Germany

^* e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

In the light of the new data on the various neutron and proton electromagnetic form factors taken in recent years, we update the dispersion-theoretical analysis of the nucleon electromagnetic form factors from the mid-nineties. The parametrization of the spectral functions includes constraints from unitarity, perturbative QCD, and recent measurements of the neutron charge radius. We obtain a good description of most modern form factor data, with the exception of the Jefferson Lab data on G _E ^p /G _M ^p in the four-momentum transfer range GeV². For the magnetic radii of the proton and the neutron we find r _M ^p = 0.857 fm and r _M ⁿ = 0.879 fm, which is consistent with the recent determinations using continued-fraction expansions.