EPJ

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EPJ C - Particles and Fields
Particles and Fields


Eur. Phys. J. C 18, 447-460
DOI: 10.1007/s100520100580

Production rates of $\mathrm{b\overline{b}}$ quark pairs from gluons and $\mathrm{b\overline{b}b\overline{b}}$ events in hadronic Z0 decays

The OPAL Collaboration G. Abbiendi and et al.

Dipartimento di Fisica dell' Università di Bologna and INFN, 40126 Bologna, Italy

(Received: 9 June 2000 / Published online: 23 January 2001 -© Società Italiana di Fisica, Springer-Verlag 2001)

Abstract
The rates are measured per hadronic Z0 decay for gluon splitting to $\mathrm{b\overline{b}}$ quark pairs, $g_{\mathrm{b\overline{b}}}$, and of events containing two $\mathrm{b\overline{b}}$ quark pairs, g4b, using a sample of four-jet events selected from data collected with the OPAL detector. Events with an enhanced signal of gluon splitting to $\mathrm{b\overline{b}}$ quarks are selected if two of the jets are close in phase-space and contain detached secondary vertices. For the event sample containing two $\mathrm{b\overline{b}}$ quark pairs, three of the four jets are required to have a significantly detached secondary vertex. Information from the event topology is combined in a likelihood fit to extract the values of $g_{\mathrm{b\overline{b}}}$ and g4b, namely

\begin{displaymath}g_{\mathrm{b\overline{b}}} = (3.07 \pm 0.53 \mathrm{(stat)} \pm 0.97\mathrm{(syst)})\times 10^{-3}, \end{displaymath}


\begin{displaymath}g_{\mathrm{4b}} = (0.36\pm 0.17 \mathrm{(stat)} \pm 0.27\mathrm{(syst)})\times 10^{-3}. \end{displaymath}



© Società Italiana di Fisica, Springer-Verlag 2001

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