Universit . . at Bonn Physikalisches Institut and K 0 S Production in Quark and Gluon Jets Classified by Energy-ordering

The production of baryons and K 0 S mesons in quark and gluon jets has been investigated in 3-jet events using 2.8 million hadronic Z 0 decays recorded with the OPAL detector at LEP. The events were selected with various jet nding algorithms resulting in jet samples of somewhat diierent topologies. The jets were classiied according to their energy with the aid of Monte Carlo models: the lowest energy jets were assumed to be mostly gluon jets. and K 0 S production rates in the jets, normalized to the charged multiplicity, have been determined. These relative production rates have been found to be larger in gluon jets than in quark jets by 30{40 % for baryons, and by about 8% for K 0 S mesons, depending slightly on the average jet topology. Experimentally the relative rates were found to be independent of the jet energy and the interjet angle for both quark and gluon jets. This allows to compare the absolute rates of and K 0 S production in quark and gluon jets in symmetric, Y-shaped 3-jet events using our relative rates and the published charged particle rates. The experimental results have been compared with the Jetset predictions, which generally underestimate the enhanced relative and K 0 S production rates in gluon jets, and with the predictions of the Cojets and Herwig Monte Carlo models, which both fail to describe the experimental distributions .