Speaker
Description
We investigate the electromagnetic form factors of the nucleon using
an effective chiral theory based on the QCD instanton vacuum.
Here we take into account the momentum-dependent dynamical quark mass
originating from the instanton-induced 2$N_f$ quark interactions.
The momentum-dependent quark mass naturally plays the role of a regulator,
so that no additional regularization is needed. Since the dynamical
quark mass at zero virtuality is fixed by the saddle-point equation beyond
the chiral limit, there is no adjustable free parameter.
Within this framework, we evaluate the proton and neutron electric and
magnetic form factors, charge and magnetization densities, and related
observables. We also compare the results with the chiral quark-soliton model
and the Kelly parametrization. The results are in good agreement with the
experimental data and show that the contributions from the momentum
dependence are not negligible. This study implies that the effective
chiral theory derived from the QCD instanton vacuum gives a consistent
framework to describe the nucleon electromagnetic structure.
