New analysis of the radiative decay ω→ηγ\omega \to \eta\gamma in proton-antiproton annihilation at rest

We report on a measurement of the branching ratio of the rare decay omega to eta gamma relative to the well known decay omega to pi /sup 0/ gamma . The omega 's are produced in pp to eta omega and pp to pi /sup 0/ omega . Eigenstate mixing and interference effects of the omega and rho /sup 0/ are taken into account, as well as coherent interference with the background. We find evidence for the non- resonant annihilation channel B(pp to eta eta gamma )=(3.5+or-1.3)*10 /sup -5/ and limit the value of B( omega to eta gamma ) to the range of (0.7 to 5.5)*10/sup -4/ depending on the degree of coherence with the background. (19 refs)