Current algebra and the η3π decaydecay

Abstract

The general current-algebra-pion-PCAC constraints on theη → 3π decay amplitude are formulated independently of any model of the semi-strong and electromagnetic Hamiltonian. A wide range of models for the Hamiltonian are reviewed, and it is found that the electromagnetic « tadpole » necessary to account for electromagnetic mass splittings of hadrons is also necessary to account for theη → 3π decay. With the presence of this « tadpole » there is no PCAC problem: the background amplitude is smooth in the pion momenta. In the particular model of (3, $$\bar 3$$ ) breaking, theη → 3π decay rates are found to be not incompatible with experiment.