A study of charm and anti-charm production in beauty decays with the OPAL detector at LEP

The branching ratio of beauty hadrons to final states containing two charm hadrons, Br(b \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\to \mathrm{D\bar{D}X}$\end{document}, has been measured using an inclusive method in hadronic Z0 decays with the OPAL detector at LEP. The impact parameter significance of tracks opposite tagged b-jets is used to differentiate b \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\to \mathrm{D\bar{D}X}$\end{document} decays from other decays. The result is \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \mathrm{Br(b} \to \mathrm{D\bar{D}X}) = (10.0 \pm 3.2 (\mathrm{stat.})^{+2.4}_{-2.9}(\mathrm{det.})^{+10.4}_{-9.0} (\mathrm{phys.}))\%,$$\end{document} where “det.” is the systematic uncertainty due to the modelling of the detector, and “\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}${\rm phys.}$\end{document}” is the systematic uncertainty due to the modelling of the underlying physics. Using this result, the average number of charm plus anti-charm quarks produced in a beauty quark decay, nc, is found to be 1.12 + 0.11-0.10.