Determination of the QCD color factor ratio CA/CF from the scale dependence of multiplicity in three jet events

Abstract

I examine the determination of the QCD color factor ratio CA/CF from the scale evolution of particle multiplicity in e+e- three jet events. I fit an analytic expression for the multiplicity in three jet events to event samples generated with QCD multihadronic event generators. I demonstrate that a one parameter fit of CA/CF yields the expected result CA/CF=2.25 in the limit of asymptotically large energies if energy conservation is included in the calculation. In contrast, a two parameter fit of CA/CF and a constant offset to the gluon jet multiplicity, proposed in a recent study, does not yield CA/CF=2.25 in this limit. I apply the one parameter fit method to recently published data of the DELPHI experiment at LEP and determine the effective value of CA/CF from this technique, at the finite energy of the Z0 boson, to be 1.74+-0.03+-0.10, where the first uncertainty is statistical and the second is systematic.

20 pages including 6 figures Version 2 corrects typographical error in equation (2)

References in corpus (4)

• Experimental properties of gluon and quark jets from a point source
• The Scale Dependence of the Hadron Multiplicity in Quark and Gluon Jets and a Precise Determination of $C_A/C_F$
• Evolution of average multiplicities of quark and gluon jets
• Energy dependence of mean multiplicities in gluon and quark jets at the next-to-next-to-next-to-leading order

Cited by in corpus (2)

• Hadron Multiplicities
• Experimental Verification of Two types of Gluon Jets in QCD