COMMENT ON THE DECAY Z0 → π0γ

Abstract

The processes γ* → π0γ and Z → π0γ, for which a recent study found sizable rates, are examined. It is shown that a general procedure based on chiral anomaly and PCAC is not sufficient to fix these rates, although the standard π0 → γγ rate can be derived. Calculation of the one-loop diagrams shows that the rates are much suppressed. Two distinct formulations with massless and massive pions are presented, which give the same conclusion.