Studies of the 4-jet rate and of moments of event shape observables using JADE data

TL;DR

This study analyzes e+e- collision data from the JADE experiment to measure the 4-jet rate and moments of event shape observables, comparing results with QCD predictions to determine the strong coupling constant.

Contribution

It provides new measurements of alpha_S at different energies using the JADE data, incorporating NLO and NLLA calculations for improved accuracy.

Findings

Measured alpha_S(MZ) from 4-jet rate: 0.1169 +/- 0.0026

Measured alpha_S(MZ) from moments: 0.1286 +/- 0.0072

Some higher moments show discrepancies with QCD predictions

Abstract

Data from e+e- annihilation into hadrons collected by the JADE experiment at centre-of-mass energies between 14 and 44 GeV were used to study the 4-jet rate using the Durham algorithm as well as the first five moments of event shape observables. The data were compared with NLO QCD predictions, augmented by resummed NLLA calculations for the 4-jet rate, in order to extract values of the strong coupling constant alpha_S. The preliminary results are alpha_S(MZ) = 0.1169 +/- 0.0026 (4-jet rate) and alpha_S(MZ) = 0.1286 +/- 0.0072 (moments) consistent with the world average value. For some of the higher moments systematic deficiencies of the QCD predictions are observed.