Measurement of the semileptonic branching ratio of charm hadrons produced in Z0 → cc̄ decays

The inclusive charm hadron semileptonic branching fractions \({\rm B}({\rm c}\to{\rm e})\) and \({\rm B}({\rm c}\to\mu)\) in \(\mathrm{Z}^0\to\mathrm c\bar{\mathrm c}\) events have been determined using 4.4 million hadronic \(\mathrm{Z}^0\) decays collected with the OPAL detector at LEP. A charm-enriched sample is obtained by selecting events with reconstructed \(\mathrm{D}^{*\pm}\) mesons. Using leptons found in the hemisphere opposite that of the \(\mathrm{D}^{*\pm}\) mesons, the semileptonic branching fractions of charm hadrons are measured to be \(\) where the first errors are in each case statistical and the second systematic. Combining these measurements, an inclusive semileptonic branching fraction of charm hadrons of \(\) is obtained.