Measurement of the ω→ηγ decay rate

The branching ratio of the rare radiative decay ω→ηγ has been measured: BR(ω→ηγ)=(8.3±2.1)·10−4. The experiment was performed at the IHEP (Serpukhov) accelerator with 38 GeV/c incident pions in the chargeexchange reaction π-p→ωn the photons from the ω→ηγ→3γ decay being detected with the multiphoton spectrometer GAMS-2000. The influence of ω-ρ mixing, which was a source of ambiguity in the interpretation of previous experiments, has been much reduced by measuring the ω produced at large momentum transfer.