Determination of the strong coupling constant $\alpha_{S}(m_\mathrm{Z})$ from measurements of inclusive W$^\pm$ and Z boson production cross sections in proton-proton collisions at $\sqrt{s} =$ 7 and 8 TeV

TL;DR

This paper measures inclusive W and Z boson production cross sections at 7 and 8 TeV in proton-proton collisions, compares them with NNLO QCD predictions, and extracts the strong coupling constant _S(m_Z) with improved precision.

Contribution

It introduces a novel procedure for extracting _S(m_Z) from multiple cross section measurements and theoretical predictions, enhancing the precision of _S(m_Z) determination.

Findings

_S(m_Z) = 0.1175^{+0.0025}_{-0.0028} from combined analysis.

Good agreement between data and NNLO QCD predictions across PDF sets.

The method improves the robustness and stability of _S(m_Z) extraction.

Abstract

Twelve measurements of inclusive cross sections of W$^\pm$ and Z boson production, performed in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV, are compared with perturbative quantum chromodynamics calculations at next-to-next-to-leading order (NNLO) accuracy obtained with the CT14, HERAPDF2.0, MMHT14, and NNPDF3.0 parton distribution functions (PDFs). Data and theory agree well for all PDF sets, taking into account the experimental and theoretical uncertainties. A novel procedure is employed to extract the strong coupling constant at the Z pole mass from a detailed comparison of all the experimental fiducial cross sections to the corresponding NNLO theoretical predictions, yielding $\alpha_{S}(m_\mathrm{Z}) =$ 0.1163 $^{+0.0024}_{-0.0031}$ (CT14), 0.1072 $^{+0.0043}_{-0.0040}$ (HERAPDF2.0), 0.1186 $\pm$ 0.0025 (MMHT14), and 0.1147 $\pm$ 0.0023 (NNPDF3.0). Using the results obtained with the CT14 and MMHT14 PDFs, which yield the most robust and stable $\alpha_{S}(m_\mathrm{Z})$ extractions, a value $\alpha_{S}(m_\mathrm{Z}) =$ 0.1175 $^{+0.0025}_{-0.0028}$ is determined.