Production of Massive Muon Pairs by 300- and 400-GeV Protons

Abstract

We have observed muon pairs with effective masses in the range $7<~M_{\mu \mu }<~11$ GeV/${\mathit{c}}^2$ produced by 300- and 400-GeV protons incident on a Cu target at Fermilab. The production cross section per nucleon, $\frac{d\sigma }{d{M}_{\mu \mu }}$, for 400-GeV incident protons is found to fall from 1 × ${10}^{-36\mathrm{}}$ ${\mathrm{cm}}^2$/(GeV/${\mathit{c}}^2$) at $M_{\mu \mu }=7.7\mathrm{}$ GeV/${\mathit{c}}^2$ to 2.7 × ${10}^{-38\mathrm{}}$ ${\mathrm{cm}}^2$/(GeV/${\mathit{c}}^2$) at $M_{\mu \mu }=11.2\mathrm{}$ GeV/${\mathit{c}}^2$. We find that a significant fraction of the observed direct single muons come from high-mass dimuons.