The Strong Coupling: Measurements and Running

TL;DR

This paper reviews recent measurements of the strong coupling constant _s from e+e- annihilation event shapes, discusses scale setting issues, power corrections, and summarizes current _s(M_Z) results and its energy dependence.

Contribution

It provides a comprehensive overview of recent experimental and theoretical developments in determining _s, highlighting issues with scale choices and power corrections.

Findings

Recent _s measurements show consistency within uncertainties.

Problems observed with NLLA predictions highlight theoretical challenges.

Power corrections are significant for understanding energy evolution of event shapes.

Abstract

Measurements of \alpha_s from event shapes in e^{+} e^{-} annihilation are discussed including recent determinations using experimentally optimized scales, studies of theoretically motivated scale setting prescriptions, and recently observed problems with predictions in Next to Leading Logarithmic Approximation. Other recent precision measurements of \alpha_s are briefly discussed. The relevance of power terms for the energy evolution of event shape means and distributions is demonstrated. Finally a summary on the current results on \alpha_s(M_Z) and its running is given.