Abstract

The rate of gluon splitting into cc̄ pairs in hadronic Z decays is measured using the data sample collected by ALEPH from 1991 to 1995. The selection is based on the identification of leptons (electrons and muons) originating from semileptonic charm decays, and on the topological properties of signal events. The result derived from the selected sample is gcc̄=(3.26±0.23(stat)±0.42(syst))%.

Highlights

  • In this letter a measurement of the production rate of cc pairs from gluons in hadronic Z decays is described

  • The selection relies on tagging semileptonic decays of the c quarks from gluon splitting, and makes use of several discriminating variables related to the event topology

  • The rate of gluon splitting to cc pairs is defined as gcc

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Summary

Introduction

In this letter a measurement of the production rate of cc pairs from gluons in hadronic Z decays is described. The selection relies on tagging semileptonic decays of the c quarks from gluon splitting, and makes use of several discriminating variables related to the event topology. The processes g → cc and g → bbare significant backgrounds for several analyses involving heavy quarks. Gluon splitting to heavy quarks is a background for Higgs boson searches [2]. The theoretical treatment of the production of heavy quarks from gluons is described in [3, 4, 5, 6] and the rate gcc is predicted to be in the range 1.4% to 2.5%.

The ALEPH detector
Preselection
The extraction of gcc
Systematic errors
Stability of the neural network cuts
Shape of Ne and Nμ
Results and conclusions
Full Text
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