Multiplicities of π 0, η, K 0 and of charged particles in quark and gluon jets

Abstract

We measured the average multiplicities of inclusive charged particles, π 0, η and K 0 mesons in quark and in gluon jets as a function of a topological scale Q jet. The ratio of particle multiplicity in gluon jets to that in quark jets as a function of Q jet is found to be independent of the particle species, which is consistent with QCD expectation. We observed no evidence for an enhancement of η meson production in gluon jets with respect to quark jets, beyond that observed for charged particles. We measured the ratio of the slope of the average charged particle multiplicity in gluon jets to that in quark jets, C, and we compared it to a next-to-next-to-next-to leading order calculation. Our result, C = 2.27 ± 0.20(stat. + syst.), is about one standard deviation higher than the perturbative prediction.