Nucleon properties in the covariant quark-diquark model
Institut für Theoretische Physik, Universität Tübingen, Auf der Morgenstelle 14, 72076, Tübingen, Germany
2 Institut für Theoretische Physik III, Universität Erlangen-Nürnberg, Staudtstr. 7, 91058, Erlangen, Germany
Published online: 15 August 2000
In the covariant quark-diquark model the effective Bethe-Salpeter (BS) equations for the nucleon and the Δ are solved including scalar and axial vector diquark correlations. Their quark substructure is effectively taken into account in both, the interaction kernel of the BS equations and the currents employed to calculate nucleon observables. Electromagnetic current conservation is maintained. The electric form factors of proton and neutron match the data. Their magnetic moments improve considerably by including axial vector diquarks and photon induced scalar-axial vector transitions. The isoscalar magnetic moment can be reproduced, the isovector contribution is about 15% too small. The ratio µG E/G M and the axial and strong couplings g A, g πNN, provide an upper bound on the relative importance of axial vector diquarks confirming that scalar diquarks nevertheless describe the dominant 2-quark correlations inside nucleons.
PACS: 11.10.St Bound states; Bethe-Salpeter equations – / 12.40.Yx Hadron mass models and calculations – / 13.40.Gp Electromagnetic form factors – / 14.20.Dh Protons and neutrons –
© Società Italiana di Fisica and Springer-Verlag, 2000