Two-photon processes of pseudoscalar mesons in a Bethe-Salpeter approach

We evaluate the π0γ∗ → γ transition form factor and γγ decay widths for π0, ηc and ηb treated as qq bound states in the Bethe-Salpeter formalism, incorporating the dynamical chiral symmetry breaking and the Goldstone nature of the pion. In the chiral limit, the Abelian axial anomaly is incorporated analytically in our coupled Schwinger-Dyson and Bethe-Salpeter approach, which is also capable of quantitatively describing systems of heavy quarks, concretely ηc and possibly ηb.