engleski

Two-photon decays of $pi^0, eta_c$ and $ eta_b$ in a Bethe-Salpeter approach

We calculate the widths for the decays of $pi^0, eta_c$ and $eta_b$ into two photons. We treat $pi^0, eta_c$ and $eta_b$ as the $qar{q}$ bound states in the Bethe--Salpeter formalism, incorporating the dynamical chiral symmetry breaking and the (pseudo) Goldstone nature of the pion. We use the dressed, Ball--Chiu electromagnetic quark vertices, consistent with our dressed quark propagators. This enables us to incorporate the Abelian axial anomaly correctly in our Bethe--Salpeter approach, as demonstrated by its ability to give analytically, in the chiral limit, the famous axial anomaly result for the $pi^0 ogammagamma$ decay. The same framework is also capable of describing systems of heavy quarks, concretely $eta_c$ and possibly $eta_b$, and their $gammagamma$ decays.

hadronic structure; QCD; Schwinger-Dyson equations; Bethe-Salpeter equations; electromagnetic; axial anomaly

nije evidentirano