Observation of Prompt Single Muons and Dimuons in Hadron-Nucleus Collisions at 200 GeV/<i>c</i>

Abstract

We trigger a large-acceptance spectrometer by single muons and observe any additional muons with good efficiency. The effect of $\ensuremath{\pi}$ and $K$ decays is subtracted to obtain the prompt muon signal in the kinematic region $0.1&lt;x&lt;0.4$ and ${p}_{T}&lt;1.0$ GeV/c. We find 0.7 \ifmmode\pm\else\textpm\fi{} 0.2 of all prompt $\ensuremath{\mu}'\mathrm{s}$ are produced in pairs; the $\frac{\ensuremath{\mu}}{\ensuremath{\pi}}$ ratio decreases with $x$ but increases with ${p}_{T}$, averaging 3 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}5}$.