Two-component model for the axial form factor of the nucleon

Abstract

The axial form factor of the nucleon is studied in a two-component model consisting of a three-quark intrinsic structure surrounded by a meson cloud. The experimental data in the space-like region are well reproduced with a minimal number of parameters. The results are similar to those obtained from a dipole fit for $0l{Q}^{2}l1 {\mathrm{GeV}}^{2}$, but outside this region there are important deviations from the dipole parametrization. Finally, the theoretical formula for the axial form factor is extrapolated by analytic continuation to the time-like region, thus providing the first predictions in this kinematical region which is of interest for present and future colliders.