Upper Limits for the Production of Light Short-Lived Neutral Particles in Radiative $\Upsilon$ decay

We have searched for the exclusive decay of the $\Upsilon \mathrm{}\left(1S\right)\mathrm{}$ into a photon and a short-lived spin-0 particle, $a$, decaying into $e^{+}{e}^{-}$, using the CLEO detector at the Cornell Electron Storage Ring. Upper limits for the product branching ratio $B\left(\Upsilon \mathrm{}\right(1S)\mathrm{}\to \gamma a)B(a\to e^{+}{e}^{-})$ are established for a range of masses, $2m_e<m_a<2\mathrm{}{m}_{\mu }$.