The off-shell axial anomaly via the γ∗π0 → γ transition

The γ∗π0 → γ form factor, including the extension off the pion mass-shell, is obtained from a generalized impulse approximation within a QCD-based model field theory known to provide an excellent description of the pion charge form factor. This approach implements dressing of the vertices and propagators consistent with dynamical chiral symmetry breaking, gauge invariance, quark confinement and perturbative QCD. Nonperturbative behavior at the real photon vertex is found to generate a logarithmic correction to the large spacelike-q2 behavior.