Measurement of alpha-s from energy-energy correlations at the Z0 resonance

TL;DR

This paper measures the strong coupling constant alpha-s at the Z0 resonance using energy-energy correlations in hadronic Z0 decays, comparing experimental data with various QCD predictions to evaluate theoretical uncertainties.

Contribution

It provides a comprehensive analysis of alpha-s extraction from EEC and AEEC, highlighting discrepancies among QCD calculations and demonstrating the reduction of scale ambiguity with matched predictions.

Findings

Alpha-s(MZ)=0.124 with combined experimental and theoretical uncertainties.

Large discrepancies observed among different O(alpha-s**2) QCD calculations.

Matched calculations significantly reduce renormalization scale ambiguity.

Abstract

We have determined the strong coupling alpha-s from a comprehensive study of energy-energy correlations (EEC) and their asymmetry (AEEC) in hadronic decays of Z0 bosons collected by the SLD experiment at SLAC. The data were compared with all four available predictions of QCD calculated up to O(alpha-s**2) in perturbation theory, and also with a resummed calculation matched to all four of these calculations. We find large discrepancies between alpha-s values extracted from the different O(alpha-s**2) calculations. We also find a large renormalization scale ambiguity in alpha-s determined from the EEC using the O(alpha-s**2) calculations; this ambiguity is reduced in the case of the AEEC, and is very small when the matched calculations are used. Averaging over all calculations, and over the EEC and AEEC results, we obtain alpha-s(MZ)=0.124+0.003-0.004(exp.) +-0.009(theory).