PoS - Proceedings of Science
Volume 365 - alphas-2019: Workshop on precision measurements of the QCD coupling constant (ALPHAS2019) - $a_S$ from electroweak observables
High-precision $α_S$ from W and Z hadronic decays
D. d’Enterria
Full text: pdf
Pre-published on: July 23, 2019
Published on: September 13, 2019
The extraction of the QCD coupling $\alpha_s$ from the comparison of experimental data on inclusive W and Z bosons hadronic decays to state-of-the-art perturbative QCD calculations %at N$^{3}$LO accuracy
is reviewed. The relatively small amount of W data from $e^+e^-\to$\,W$^+$\,W$^-$ collisions at LEP leads today to an non-competitive extraction of the strong coupling at the Z mass from the measured $R_W$ ratio of hadronic-to-leptonic branching fractions,
$\alpha_s(m_Z) = 0.117 \pm 0.042_{exp} \pm 0.004_{th} \pm 0.001_{par}$ with a $\sim$35\% propagated experimental uncertainty. Analysis of the much more abundant hadronic results at the Z pole leads to $\alpha_s(m_Z) = 0.1203 \pm 0.0030$, with a 2.5\% uncertainty by combining three different pseudo-observables (ratio of hadronic-to-leptonic widths $R_Z$, hadronic peak cross section
$\sigma^o_Z$, and total width $G_Z$). An $\alpha_s$ determination with per mille uncertainty requires high-statistics W and Z bosons data samples at future $e^+e-$ colliders, such as the FCC-ee, combined with even higher precision (N$^4$LO) pQCD calculations.
DOI: https://doi.org/10.22323/1.365.0008
How to cite

Metadata are provided both in "article" format (very similar to INSPIRE) as this helps creating very compact bibliographies which can be beneficial to authors and readers, and in "proceeding" format which is more detailed and complete.

Open Access
Creative Commons LicenseCopyright owned by the author(s) under the term of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.