Nucleon form factors of the isovector axial-vector current - Situation of experiments and theory

The theoretical and experimental status of the isovector axial-vector current form factors G (A)(q(2)) and G (P)(q(2)) of the nucleon is reviewed. We also describe a new calculation of these form factors in manifestly Lorentz-invariant chiral perturbation theory (ChPT) with the inclusion of axial-vector mesons as explicit degrees of freedom.