Radiative $\Upsilon \mathrm{}\left(1S\right)\mathrm{}$ decays

We report on a study of exclusive radiative decays of the $\Upsilon \mathrm{}\left(1S\right)\mathrm{}$ resonance. We have considered decays into final states of the form $\Upsilon \to \gamma n\left(h^{+}{h}^{-}\right)$, with ($h^{+}{h}^{-}$) denoting a charged-hadron pair (either ${\pi }^{+}{\pi }^{-}$, $K^{+}{K}^{-}$, or $p\overline{p}$), and $n$ denoting the number of such pairs in the event. We measure branching ratios for $n=2, 3, \mathrm{and} 4$, and search for structure in the recoiling hadronic system. For the $n=1\mathrm{}$ case, we present upper limits. No evidence is observed for two-body radiative decays of the $\Upsilon \mathrm{}\left(1S\right)\mathrm{}$ meson in any of the above channels.