Determination of the QCD color factor ratio C-A/C-F from the scale dependence of multiplicity in three jet events - art. no. 114007

I examine the determination of the QCD color factor ratio C-A/C-F from the scale evolution of particle multiplicity in e(+)e(-) three jet events. I fi t an analytic expression for the multiplicity in three jet events to event samples generated with QCD multihadronic event generators. I demonstrate th at a one parameter fit of C-A/C-F yields the expected result C-A/C-F = 2.25 in the limit of asymptotically large energies if energy conservation is in cluded in the calculation. In contrast, a two parameter fit of C-A/C-F and a constant offset to the gluon jet multiplicity, proposed in a recent study , does not yield C-A/C-F = 2.25 in this limit. I apply the one parameter fi t method to recently published data of the DELPHI experiment at the e(+)e(- ) collider LEP at CERN and determine the effective value of C-A/C-F from th is technique, at the finite energy of the Z(o) boson, to be 1.74 +/- 0.03 /- 0.10, where the first uncertainty is statistical and the second is syste matic.