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The European Physical Journal C
ISSN: 1434-6044 (printed version)
ISSN: 1434-6052 (electronic version)
Abstract Volume 4 Issue 4 (1998) pp 557-570
DOI 10.1007/s100529800939
experimental physics:
Measurement of the fraction of hadronic Z decays into charm quark pairs
The ALEPH Collaboration
, R. Barate et al.
Laboratoire de Physique des Particules (LAPP), IN2P3-CNRS, F-74019 Annecy-le-Vieux Cedex, France
Received: 6 March 1998 / Published online: 2 July 1998
Abstract. The full statistics of hadronic Z decays collected with the ALEPH detector are analysed to measure, by three methods, the ratio, ${\rm R_c}$, of the partial decay width of the Z into ${\rm c\bar c}$ quarks to the total hadronic width. One method uses the inclusive $p$ and $p_{\perp}$ spectra of electrons. The other two use a double-tagging technique to measure ${\rm R_c}$ independently of the charm-tagging efficiency. In one, the tagging procedure uses the reconstruction of high momentum charmed mesons (${\rm D^{*+}}$, ${\rm D^+}$ and ${\rm D^0}$) to detect the charm quarks. In the other, a charm quark is tagged from the ${\rm D^*}$'s reconstructed in the ${\rm D^{*+} \to \pi^+ D^0}$ decay channel and the other from the slow pion from the ${\rm D^{*-} \to \pi^- \bar{D}^0}$ decay. The combination of these measurements leads to ${\rm R_c = \Gamma(Z \to c\bar c) / \Gamma(Z \to hadrons)}) = 0.1681\pm0.0054({\rm stat})\pm0.0062({\rm syst})$.
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Online publication: July 20, 1998
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