Measurement of the Probability of Gluon Splitting into Charmed Quarks in Hadronic Z Decays

TL;DR

This paper measures the probability of gluons splitting into charm quark pairs in hadronic Z decays using two independent methods, providing a precise estimate with combined analysis.

Contribution

It introduces two novel methods—lepton tagging and neural network analysis—for measuring gluon splitting into charm quarks in Z decays.

Findings

Measured n(g->cc~)= 2.45% with uncertainties

Used 1.7 million Z decay events

Combined two independent analysis methods

Abstract

We have measured the probability, n(g->cc~), of a gluon splitting into a charm-quark pair using 1.7 million hadronic Z decays collected by the L3 detector. Two independent methods have been applied to events with a three-jet topology. One method relies on tagging charmed hadrons by identifying a lepton in the lowest energy jet. The other method uses a neural network based on global event shape parameters. Combining both methods, we measure n(g->cc~)= [2.45 +/- 0.29 +/- 0.53]%.