Coherent particle production and multiplicities in three-jet-events of Z0 annihilations

Abstract

The particle production in hadronic three-jet events from Z-decays is studied with data from the DELPHI-experiment. The topology dependence of the multiplicity produced with large angles to the event plane is compared with a LO prediction revealing a 1/ N c -suppressed destructive gluon interference. The topology dependence of the total charged event multiplicity is compared with a MLLA prediction. A parameter fit to the data results in a precise measurement of the colour factor ratio C A / C F = 2.261 ± 0.014(stat.) ± 0.036(syst.) ± 0.052(theor.) ± 0.041(clus.). The multiplicity of two-gluon systems is extracted from the measured multiplicities over a wide range of energy scale, allowing for studies of the ratio of the multiplicities of q- and gg-systems and the ratio of the derivatives of the multiplicities w.r.t. energy.