  We present a study of two-photon decays of light mesons, focusing on the
neutral pion decay. This important process highlights the effects of the axial
anomaly in QCD but has been little studied on the lattice. By applying the
Lehmann-Symanzik-Zimmermann (LSZ) reduction formula, we reconstruct the
electromagnetic matrix elements from three-point vector-vector Green functions
calculated on 2+1-flavor isotropic clover lattices.
