Truncated QCD Shower Calculation of Heavy-Quark Production in $p\overline{p}$ Collisions with $B^0-{\overline{B}}^0$ Mixing

Characteristics of $W$ production are well described by a parton-shower approximation, based solely on the $q\overline{q}\to \mathrm{Wg}$ subprocess with a low-$p_T$ cutoff chosen to reproduce the total cross section through order ${\alpha }_s$. We apply this approach to $Q\overline{Q}$ production from the 2→ 3-parton subprocesses in $p\overline{p}$ collisions. The results agree with CERN dimuon events for a $B^0-{\overline{B}}^0$ mixing parameter $\epsilon \gtrsim 0.1$, which is at the $e^{+}{e}^{-}$ experimental limit and larger than standard-model expectations.