\Upsilon(1s)-->\gamma(\eta',\eta) decays

The decays of $\mathrm{{\rm Y}}(1s)\to \gamma ({\eta }^{\mathrm{\prime }},\eta )$ are studied by an approach which has successfully predicted the ratio $\frac{\mathrm{\Gamma }(J\mathrm{/}\psi \to \gamma {\eta }^{\mathrm{\prime }})}{\mathrm{\Gamma }(J\mathrm{/}\psi \to \gamma \eta )}$. Strong dependence on quark mass has been found in the decays $(J/\psi, \Upsilon(1s))\to\gamma(\eta’,\eta)$\mathrm{.}Verysmalldecayratesof$\Upsilon(1s)\to\gamma(\eta’,\eta)$ are predicted.