Universit . . at Bonn Physikalisches Institut a Monte Carlo Study of Particle Production in Quark and Gluon Jets Classiied by Energy-ordering

Inclusive particle production in quark and gluon jets classiied via energy-ordering has been investigated in 3-jet events at the Z 0 pole. The events were selected using various jet nding algorithms. The jets with higher energies were assumed to be quark jets and the jet with lowest energy to be the gluon jet. Using the same jet nder a similar energy dependence of jet purities has been found for the fragmentation models JETSET and HERWIG, nearly independent of the detector resolution. Diierent jet nders (k T , cone) which select a somewhat modiied average 3-jet event topology also yield a diierent dependence of the jet purities on energy. It is shown that the production rates of identiied particles (e.g. K 0 and) in quark and gluon jets, albeit in diierent energy regions, can be compared after normali-zation to the charged particle rate. Depending on the particle species and on the model investigated signiicant diierences have been found between the production rates of mesons and baryons in quark and gluon jets. Measured production rates within energy-ordered jets are distorted due to confusing quark and gluon jets of similar energies. Using the determined jet purities the rates in true quark and gluon jets can be recovered irrespective of the jet nding algorithm.