Measurements of $\alpha_s$ From Scaling Violations and From $R_\tau$ at LEP

TL;DR

This paper reviews two methods used at LEP to measure the strong coupling constant, $oldsymbol{ ext{alpha}_s}$, through scaling violations in momentum distributions and QCD corrections to tau decay ratios, providing precise tests of QCD.

Contribution

It compares and analyzes two distinct experimental approaches for extracting $oldsymbol{ ext{alpha}_s}$ at LEP, highlighting their methodologies and results.

Findings

Consistent measurements of $oldsymbol{ ext{alpha}_s}$ from both methods.

Quantitative assessment of non-perturbative corrections in tau decays.

Enhanced precision in $oldsymbol{ ext{alpha}_s}$ determination at LEP.

Abstract

The results of two methods to extract the strong coupling constant, $\alpha_s$, are reviewed for the LEP experiments. In the first, scaling violations in the scaled momentum distributions of charged particles at LEP and at lower energy experiments are employed. In the second, QCD corrections to $R_\tau$, the ratio of hadronic to leptonic decay rates of the tau lepton, determine $\alpha_s$ and, using moments of the invariant mass distribution in hadronic tau decays, the non-perturbative corrections to $R_\tau$.