Chiral anomaly route to the KL → π+ π- γ decay

The increasing body of experimental data motivates us to investigate a new contribution to the radiative KL -> π^+ π^- gamma decay, which is O(π^4) within the framework of the chiral perturbation theory. The new contribution refers to the DeltaS = 1 WZW action term, established recently for the direct, O(p^4), KL -> gamma gamma(-) decay amplitude. We present additional evidence in support of such flavour-changing generalization of the WZW action term as a viable parametrisation of the anomalous radiative non-leptonic kaon decays