Studies of QCD at LEPII

TL;DR

This paper combines measurements of the strong coupling constant alpha_s from multiple experiments at LEP, analyzing event-shape distributions across a wide energy range within a unified theoretical framework, and examining associated uncertainties.

Contribution

It provides a comprehensive analysis of alpha_s measurements at LEP energies using a common theoretical approach, highlighting the impact of theoretical uncertainties.

Findings

Consistent alpha_s values across experiments and energies

Detailed study of theoretical uncertainties from missing higher orders

Validation of QCD predictions with experimental data

Abstract

A combination of measurements of alpha_s in e+e- annihilation at LEP is presented. Distributions of various event-shape variables measured by ALEPH, DELPHI, L3 and OPAL at centre-of-mass energies from 41 GeV to 206 GeV are analysed in a common theoretical framework using O(a_s**2)+NLLA predictions. The dominant theoretical uncertainties associated to missing higher orders are studied in detail.