Review on alpha_s at LEP

TL;DR

This review discusses methods to measure the strong coupling constant alpha_s at LEP, comparing perturbative predictions and hadronisation models, and presents recent DELPHI results within the context of LEP data.

Contribution

It provides a comprehensive overview of different approaches to determine alpha_s at LEP, including perturbative calculations and analytical hadronisation models, highlighting their advantages and disadvantages.

Findings

Comparison of perturbative and analytical hadronisation methods

Presentation of the latest DELPHI results on alpha_s

Summary of LEP measurements of alpha_s across energies

Abstract

To measure the strong coupling alpha_s from event shape observables two ingredients are necessary. A perturbative prediction containing the dependence of observables on alpha_s and a description of the hadronisation process to match the perturbative prediction with the hadronic data. As perturbative prediction O(alpha_s^2), NLLA and combined calculations are available. Beside the well known Monte-Carlo based models also analytical predictions, so called power corrections, exist to describe the hadronisation. Advantages and disadvantages of the different resulting methods for determining the strong coupling and its energy dependence will be discussed, the newest DELPHI results will be presented, and an overview of the LEP results will be included.