${\alpha }_s$ at Zinnowitz 2004

Abstract

A review of measurements of ${\alpha }_s$ is given, representing the status of April 2004. The results prove the energy dependence of ${\alpha }_s$ and are in excellent agreement with the expectations of Quantum Chromodynamics, QCD. Evolving all results to the rest energy of the $Z^0$ boson, the world average of ${\alpha }_s(M_Z)$ is determined from measurements which are based on QCD calculations in complete NNLO perturbation theory, giving ${\alpha }_s(M_Z)=0.1182\pm \mathrm{0.0027.}$

Comments: 8 pages, 4 figures, talk presented at the workshop Loops and Legs in Quantum Field Theory, April 2004, Zinnowitz (Germany)