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Charged particle multiplicity in three-jet events and two-gluon systems

  • The DELPHI Collaboration
Experimental Physics

Abstract.

The charged particle multiplicity in hadronic three-jet events from Z decays is investigated. The topology dependence of the event multiplicity is found to be well described by a modified leading logarithmic prediction. A parameter fit of the prediction to the data yields a measurement of the colour factor ratio C A /C F with the result

$$C_A/C_F = 2.261 \pm 0.014_{\mathrm{stat.}} \pm 0.036_{\mathrm{exp.}} \pm 0.066_{\mathrm{theo.}}$$

in agreement with the SU(3) expectation of QCD. The quark-related contribution to the event multiplicity is subtracted from the three-jet event multiplicity resulting in a measurement of the multiplicity of two-gluon colour-singlet states over a wide energy range. The ratios \(r = N_{gg}(s)/N_{q\bar q}(s)\) of the gluon and quark multiplicities and \(r^{(1)} = N_{gg}'(s)/N_{q\bar q}'(s)\) of their derivatives are compared with perturbative calculations.

While a good agreement between calculations and data is observed for r(1), larger deviations are found for r indicating that non-perturbative effects are more important for r than for r(1).

Keywords

Field Theory Elementary Particle Quantum Field Theory Charged Particle Energy Range 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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© Springer-Verlag Berlin/Heidelberg 2005

Authors and Affiliations

  • The DELPHI Collaboration

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