Intermittency and Correlations in Hadronic Z Decays

TL;DR

This study analyzes local multiplicity fluctuations and multiparticle correlations in hadronic Z decays using a large data sample, revealing genuine higher-order correlations and intermittency behavior consistent with QCD jet formation.

Contribution

First multidimensional analysis of factorial cumulants in e+e- annihilation, demonstrating genuine multiparticle correlations and intermittency effects in hadronic Z decays.

Findings

Intermittency-like behavior observed in fluctuations and correlations.

Genuine multiparticle correlations increase with dimension.

Monte Carlo models reproduce trends but underestimate magnitudes.

Abstract

A multidimensional study of local multiplicity fluctuations and multiparticle correlations of hadrons produced in Z decays is performed. The study is based on the data sample of more than 4 million events recorded with the OPAL detector at LEP. The fluctuations and correlations are analysed in terms of the normalized scaled factorial moments and cumulants up to the fifth order. The moments are observed to have intermittency-like behaviour, which is found to be more pronounced with increasing dimension. The large data sample allows for the first time a study of the factorial cumulants in e+e- annihilation. The analysis of the cumulants shows the existence of genuine multiparticle correlations with a strong intermittency rise up to higher orders. These correlations are found to be stronger in higher dimensions. The decomposition of the factorial moments into lower-order correlations shows that the dynamical fluctuations have important contributions from genuine many-particle correlations. The Monte Carlo models JETSET 7.4 and HERWIG 5.9 are found to reproduce the trend of the measured moments and cumulants but they underestimate the magnitudes. The results are found to be consistent with QCD jet formation dynamics, although additional contributions from other mechanisms in the hadronization process cannot be excluded.