Pseudoscalar decay constants and eta→3π in chiral and 1/N perturbation theory

The normal and anomalous chiral Ward identities are reexamined from the point of view of chiral and 1/N perturbation theory. Constraints of psi→etaγ and psi→eta'γ and pseudoscalar two-photon decays are imposed, yielding a system of six simultaneous equations. A solution for the pseudoscalar decay constants is found which is relatively insensitive to the quantum-chromodynamic surface term. The decay eta→3π is then calculated using these results, with good agreement with recent measurements