Nucleon form factors from a covariant quark core: Limits in their description |
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| Authors: | M. Oettel R. Alkofer |
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| Affiliation: | (1) Special Research Centre for the Subatomic Structure of Matter, University of Adelaide, Adelaide SA 5005, Australia, AU;(2) Institute for Theoretical Physics, Tübingen University, Auf der Morgenstelle 14, D-72076 Tübingen, Germany, DE |
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| 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 E and the nucleon magnetic moments are described correctly, the neutron electric form factor and the ratio G E/G 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. Received: 16 April 2002 / Accepted: 29 August 2002 / Published online: 17 January 2003 RID="a" ID="a"Supported by a Feodor-Lynen fellowship of the Alexander-von-Humboldt foundation and the Australian Research Council. RID="b" ID="b"Address after April 30: MPI für Metallforschung, Heisenbergstr. 1, 70569 Stuttgart, Germany. RID="c" ID="c"e-mail: Reinhard.Alkofer@uni-tuebingen.de Communicated by A. Sch?fer |
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| Keywords: | 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 |
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