Covariant nonlocal chiral quark model and pion-photon transition distribution amplitudes

Using a nonlocal chiral quark model with simple pole ansatz for the momentum dependence of the constituent quark mass and nonlocal currents satisfying Ward-Takahashi identities, we calculate pion-to-photon transition distribution amplitudes and relevant form factors. For vector amplitude we recover correct normalization fixed by the axial anomaly. We find that due to the nonlocality in the vector current, the value of the axial form factor at zero momentum transfer is lowered with respect to the vector form factor. Such behavior-consistent with experiment-is not seen in the local models. Where possible we compare our results to the experimental data.