2018 Impact factor 2.481
Hadrons and Nuclei
Eur. Phys. J. A 16, 95-109 (2003)
DOI: 10.1140/epja/i2002-10070-4

Nucleon form factors from a covariant quark core: Limits in their description

M. Oettel1 and R. Alkofer2

1  Special Research Centre for the Subatomic Structure of Matter, University of Adelaide, Adelaide SA 5005, Australia
2  Institute for Theoretical Physics, Tübingen University, Auf der Morgenstelle 14, D-72076 Tübingen, Germany

Reinhard.Alkofer@uni-tuebingen.de

(Received: 16 April 2002 / Published online: 17 January 2003)

Abstract
In treating the relativistic 3-quark problem, a dressed-quark propagator parameterization is used which is compatible with recent lattice data and pion observables. Furthermore 2-quark correlations are modeled as a series of quark loops in the scalar and axialvector channel. The resulting reduced Faddeev equations are solved for nucleon and delta. Nucleon electromagnetic form factors are calculated in a fully covariant and gauge-invariant scheme. Whereas the proton electric form factor $G_\ab{E}$ and the nucleon magnetic moments are described correctly, the neutron electric form factor and the ratio $G_\ab{E}/G_\ab{M}$ for the proton appear to be quenched. The influence of vector mesons on the form factors is investigated which amounts to a 25% modification of the electromagnetic proton radii within this framework.

PACS
11.10.St - Bound and unstable states; Bethe-Salpeter equations.
12.39.Ki - Relativistic quark model.
13.40.Gp - Electromagnetic form factors.
14.20.Dh - Protons and neutrons.

© Società Italiana di Fisica, Springer-Verlag 2003