Small-Angle Muon and Bottom-Quark Production in $\mathit{p}\overline{\mathit{p}}$ Collisions at $\surd \mathit{s}=1.8\mathrm{}\mathrm{TeV}$

This Letter describes a measurement of the muon cross section originating from $b$-quark decay in the forward rapidity range $2.4<\mathrm{}|y^{\mu }|<3.2\mathrm{}$ in $p\overline{p}$ collisions at $\sqrt{s}=1.8\mathrm{}\mathrm{TeV}$. The data used in this analysis were collected by the D0 experiment at the Fermilab Tevatron. We find that next-to-leading-order QCD calculations underestimate $b$-quark production by a factor of 4 in the forward rapidity region.