Measurement of the fraction of hadronic Z decays into charm quark pairs

Abstract

Abstract.

The full statistics of hadronic Z decays collected with the ALEPH detector are analysed to measure, by three methods, the ratio, , of the partial decay width of the Z into quarks to the total hadronic width. One method uses the inclusive and spectra of electrons. The other two use a double-tagging technique to measure independently of the charm-tagging efficiency. In one, the tagging procedure uses the reconstruction of high momentum charmed mesons (, and to detect the charm quarks. In the other, a charm quark is tagged from the 's reconstructed in the decay channel and the other from the slow pion from the decay. The combination of these measurements leads to .