γ3π and π2γ form factors from dynamical constituent quarks

We study the form factors of the low-energy anomalous π2γ and γ3π processes in the nonlocal chiral quark model which incorporates the momentum dependence of the dynamical quark mass and realizes correctly the chiral symmetries. The obtained slope parameter for π2γ is in reasonable agreement with the direct experimental results but smaller than the ones invoking vector meson dominance. Our result for the γ3π form factor interpolates between the two extremes of theoretical approaches, with the largest one provided by the vector meson dominance and the smallest one by the Schwinger–Dyson approach. But all of them are well below the single data point available so far. This situation will hopefully be clarified by the experiments at CEBAF and CERN.