A study of mean sub-jet multiplicities in two- and three-jet hadronic Z0 decays

The OPAL Collaboration

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18 Scopus citations


This paper describes an analysis of sub-jet multiplicities, which are expected to be sensitive to the properties of soft gluon radiation, in hadronic decays of the Z0. Two- and three-jet event samples are selected using the k jet clustering algorithm at a jet resolution scale y1. The mean sub-jet multiplicity as a function of the sub-jet resolution, y0, is determined separately for both event samples by reapplying the same jet algorithm at resolution scales y0<y1. These measurements are compared with recent perturbative QCD calculations based on the summation of leading and next-to-leading logarithms, and with QCD Monte Carlo models. The analytic calculations provide a good description of the sub-jet multiplicity seen in three- and two-jet mvents in the perturbative region (y0≈y1)), and the measured form of the data is in agreement with the expectation based on coherence of soft gluon radiation. The analysis provides good discrimination between Monte Carlo models, and those with a coherent parton shower are preferred by the data. The analysis suggests that coherence effects are present in the data.

Original languageEnglish
Pages (from-to)363-375
Number of pages13
JournalEuropean Physical Journal C
Issue number3
StatePublished - 1 Sep 1994
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)


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