New results on the rare, doubly radiative decay η→π0γ γ have been obtained from a revised analysis of the Crystal Ball experiment performed at the AGS. The analysis yields the first information on the dependence of the decay width, Γ(η→π0γγ), on the two-photon invariant mass squared, m2(γγ). A re-evaluation of the branching ratio is also made, BR(η→π0γγ)=(2. 21±0.24stat±0.47syst)×10-4; it implies that the decay width is Γ(η→π0γγ)=0.285±0.031stat±0. 061syst eV. These results are close to predictions based on chiral perturbation theory with vector-meson dominance.
ASJC Scopus subject areas
- Nuclear and High Energy Physics