Study of e(+)e(-) -> Upsilon(1S, 2S)eta and e(+)e(-) -> Upsilon(1S)eta ' at root s=10.866 GeV with the Belle detector

We report the first observation of the processes e+e-→D(1S,2S)η at s=10.866 GeV, with significance exceeding 10σ for both processes. The measured Born cross sections are σ(e+e-→D(2S)η)=2.07±0.21±0.19 pb, and σ(e+e-→D(1S)η)=0.42±0.08±0.04 pb. We also set the upper limit on the cross section of the process e+e-→D(1S)η′ to be σ(e+e-→D(1S)η′)<0.037 pb at 90% C.L. The results are obtained with the data sample collected with the Belle detector at the KEKB asymmetric-energy e+e- collider in the energy range from 10.63 to 11.02 GeV.