Experimental Tests of Asymptotic Freedom

Abstract

Measurements which probe the energy dependence of ${\alpha }_s$, the coupling strength of the strong interaction, are reviewed. Jet counting in $e^{+}{e}^{-}$ annihilation, combining results obtained in the centre of mass energy range from 22 to 133 GeV, provides direct evidence for an asymptotically free coupling, without the need to determine explicit values of ${\alpha }_s$. Recent results from jet production in $ep$ and in $p\overline{p}$ collisions, obtained in single experiments spanning large ranges of momentum transfer, $Q^2$, are in good agreement with the running of ${\alpha }_s$ as predicted by QCD. Mass spectra of hadronic decays of $\tau$-leptons are analysed to probe the running ${\alpha }_s$ in the very low energy domain, $0.7Ge{V}^2<Q^2<M_{\tau }^2$. An update of the world summary of measurements of ${\alpha }_s(Q^2)$ consistently proves the energy dependence of ${\alpha }_s$ and results in a combined average of ${\alpha }_s(M_Z)=0.118\pm 0.006$.

11 pages, 8 Figures, LaTeX. To appear in Proc. of QCD Euroconference 96 at Montpellier, France, July 1996

References in corpus (8)

• Big Bang Nucleosynthesis (in "The Review of Particle Properties" 2004)
• Determination of ${\alpha }_s$ and the Nucleon Spin Decomposition Using Recent Polarized Structure Function Data
• QCD tests from $e^+e^- \rar I=1~$ hadrons data and implication on the value of ${\alpha }_s$ from $\tau$-decays
• A Precise Determination of ${\alpha }_s$ from Lattice QCD
• Measurement of ${\alpha }_S$ from Jet Rates in Deep Inelastic Scattering at HERA
• Test of the Running of ${\alpha }_s$ in $\tau$ Decays
• Determination of alpha_s from F_2^p at HERA
• Directions in High Energy Physics

Cited by in corpus (7)

• Experimental Tests of Asymptotic Freedom
• Structure Functions of the Nucleon and their Interpretation
• Next-to-Leading Order QCD Corrections to Three-Jet Cross Sections with Massive Quarks
• Decay Constants of B and D Mesons from Non-perturbatively Improved Lattice QCD
• B^0_{d,s} - \bar{B}^0_{d,s} mass-differences from QCD spectral sum rules
• Tau Lepton Physics: Theory Overview
• QCD Tests from Tau Decays