Recent Results on Particle Production from Opal

Three recent OPAL studies are presented in which the fragmentation process in quark and gluon jets and in identified up, down and strange flavour jets is studied. The first is a measurement is of charged particle, π, η and K multiplicities in quark and gluon jets. No evidence is found for a particle species dependent multiplicity enhancement in gluon jets. In another study leading π, K, K S , p(p̄) and Λ(Λ̄) rates have been measured in up, down and strange flavour jets. The results confirm the leading particle effect in the fragmentation of light flavour jets. In addition a direct determination of the strangeness suppression factor has been performed, yielding γs = 0.422 ± 0.049 (stat.) ± 0.059 (syst.). In a third study mean charged particle multiplicities were measured for up, down and strange flavoured Z decays and found to be identical within the uncertainties of the measurement, as expected from the flavour independence of the strong interaction.