Contribution of the a1 meson to the axial nucleon-to-delta transition form factors

We analyze the low-Q(2) behavior of the axial form factor G(A)(Q(2)), the induced pseudoscalar form factor GP(Q(2)), and the axial nucleon-to-delta transition form factors C-5(A)(Q(2)) and C-6(A) (Q(2)). Building on the results of chiral perturbation theory, we first discuss G(A)(Q(2)) in a chiral effective-Lagrangian model including the a(1) meson and determine the relevant coupling parameters from a fit to experimental data. With this information, the form factor G(P)(Q(2)) can be predicted. For the determination of the transition form factor C-5(A)(Q(2)), we make use of an S-U(6) spin-flavor quark-model relation to fix two coupling constants such that only one free parameter is left. Finally, the transition form factor C-6(A)(Q(2)) can be predicted in terms of G(P)(Q(2)), the mean-square axial radius < r(A)(2)> Ai, and the mean-square axial nucleon-todelta transition radius < r(AN Delta)(2)>.