The enhancement of the decay ϒ(1D)→ηϒ(1S) by the axial anomaly in QCD

It is shown that the rates of the decays ϒ(1 3D1)→ηϒ(1S) and ϒ(1 3D2)→ηϒ(1S) should be comparable to and likely exceed that of the recently discussed in the literature two-pion transition ϒ(1D)→ππϒ(1S). The reason for this behavior is that the discussed η transitions are enhanced by the contribution of the anomaly in the flavor singlet axial current in QCD.