  We investigate the most interesting decay processes involving axions, photons
and the lightest pseudoscalar mesons, making use of a chiral effective
Lagrangian model with $L=3$ light quark flavors, which also includes the
flavor-singlet pseudoscalar meson and implements the $U(1)$ axial anomaly of
the fundamental theory. In particular, we compute the electromagnetic coupling
of the axion to photons and we compare our result with the prediction of the
Chiral Effective Lagrangian with $L=2$ light quark flavors. Moreover, we study
the decay channels $\eta/\eta'\rightarrow \pi\pi a$ and we estimate the
corresponding decay widths, using the existing bounds on the $U(1)_{PQ}$
breaking scale.
