Study of $e^+e^-to Upsilon(rm1S,2S)eta$ and $e^+e^-to Upsilon(rm 1S)eta^{prime}$ at $sqrt{s}=10.866$ GeV with the Belle detector

We report the first observation of the processes $e^+e^-toUpsilon(rm 1S,2S)eta$ at $sqrt{s}=10.866$~GeV with a $10.2sigma$ and $16.5sigma$ significance respectively. The measured Born cross sections are $sigma(e^+e^- to Upsilon(2S)eta)=2.07 pm 0.21 pm 0.19$~pb, and $sigma(e^+e^- to Upsilon(rm 1S)eta)=0.42 pm 0.08 pm 0.04$~pb. We also set the upper limit on the cross section of the process $e^+e^- to Upsilon(rm 1S)eta^{prime}$ to be $sigma(e^+e^- to Upsilon(rm 1S)eta^{prime})<0.035$~pb at $90%$ CL. 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 $10.63$~GeV to $11.02$~GeV.