Production of Muon Pairs by 150-GeV/c ${\pi }^{+}$ and Protons

We have measured the cross section for ${\mu }^{+}{\mu }^{-}$ production in the reactions $({\pi }^{+}, p)+\mathrm{Be}\to {\mu }^{+}+{\mu }^{-}+X$, at an incident momentum of 150 GeV/c. This Letter covers the pairs with masses above 2 GeV/${\mathit{c}}^2$, in which region the signal is dominated by production of the $J\left(3.1\right)\mathrm{}$. No events with $\mu$-pair mass >4.1 GeV/${\mathit{c}}^2$ were seen, although the experiment is sensitive up to ≥12 GeV/${\mathit{c}}^2$.