Test of QCD Analytic Predictions for Gluon and Quark Jet Differences

TL;DR

This paper introduces a new method to compare gluon and quark jet properties, enabling quantitative tests of QCD predictions and confirming the predicted ratio of charged particle multiplicities.

Contribution

A novel inclusive jet definition method is proposed, allowing direct comparison of gluon and quark jets with theoretical calculations.

Findings

Measured ratio of charged particle multiplicities: 1.552+-0.041(stat.)+-0.061(syst.)

Results agree with recent analytic QCD predictions

Method bridges gap between experimental and theoretical jet definitions

Abstract

Differences between the properties of gluon and quark jets have been convincingly established by experiments at LEP. Quantitative tests of QCD analytic predictions for these differences have not been possible, however, because of differences between the theoretical and experimental definitions of the jets and event samples. Here, a new method to compare gluon and quark jet properties is described, which uses an inclusive definition of the jets in analogy to theoretical calculations. Using this new method, a value 1.552+-0.041(stat.)+-0.061(syst.) is found for the ratio of the mean charged particle multiplicity in gluon jets to that in quark jets, in agreement with a recent analytic calculation which incorporates energy conservation.