Measurements of the production of the weakly decaying charmed hadrons: D 0 , D + , D + s and + c in both Z 0 ! c c and Z 0 ! b b events are reported. By summing the partial contributions from each of these states we measure the partial width for Z 0 decays into a c c pair as:
Symmetric three-jet events are selected from hadronic Z 0 decays such that the two l o w er energy jets are each produced at an angle of about 150 with respect to the highest energy jet. In some cases, a displaced secondary vertex is reconstructed in one of the two l o w er energy jets, which permits the other lower energy jet to be identied as a gluon jet through anti-tagging. In other cases, the highest energy jet is tagged as a b jet or as a light quark (uds) jet using secondary vertex or track impact parameter and momentum information. Comparing the two lower energy jets of the events with a tag in the highest energy jet to the anti-tagged gluon jets yields a direct comparison of b, uds and gluon jets, which are produced with the same energy of about 24 GeV and under the same conditions. We observe b jets and gluon jets to have similar properties as measured by the angular distribution of particle energy around the jet directions and by the fragmentation functions. In contrast, gluon jets are found to be signicantly broader and to have a markedly softer fragmentation function than uds jets. For the k ? jet nder, we nd hn ch: i gluon hn ch: i b quark = 1:089 0:024 (stat:) 0:024 (syst:) hn ch: i gluon hn ch: i udsquark = 1:390 0:038 (stat:) 0:032 (syst:) as the ratios of the mean charged particle multiplicity in the gluon jets compared to the b and uds jets. Results are also reported using the cone jet nder.
A search for the hadronic decay o f a h ypothetical resonance S 0 in the process e + e + hadrons at Z 0 energies is reported. Particular care is taken to optimise the sensitivity to a scalar resonance decaying into bottom quarks, as expected for Higgs production, e + e Z 0 H 0 with H 0 b b, in the Standard Model or some of its extensions. No evidence for such a resonance is observed in a sample of about 5 million produced Z 0 's. The results are interpreted in terms of models of non-standard Higgs production. An update of a search for a resonance produced in association with hadrons and the subsequent resonance decay i n to two photons is also presented.
A measurement of the forward-backward asymmetries of e + e !Z 0 !bb and e + e !Z 0 !cc using electrons and muons produced in semileptonic decays of bottom and charm hadrons is presented. Two new variables designed to optimize avour separation are used in a maximum likelihood t to a sample of events containing one or two identied leptons, allowing the simultaneous extraction of the b and c quark forward-backward asymmetries as well as the average B 0-B 0 mixing. Using all data collected by O P AL up to the end of 1994, the asymmetries are measured to be:
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