Limit onϒMuoproduction at 209 GeV

We present the dimuon mass spectrum from 102 678 three-muon final states produced by muon interactions within a magnetized steel calorimeter. The data place a 90%-confidence-level upper limit on the production of $\Upsilon$ states by muons: $\sigma (\mu N\to \mu \Upsilon X)B(\Upsilon \to {\mu }^{+}{\mu }^{-})<\mathrm{}22\mathrm{}\times {10}^{-39\mathrm{}}$ ${\mathrm{cm}}^2$, consistent with a photon-gluon-fusion model calculation.