Determination of the strong coupling constant ${\alpha }_s(m_Z)$ from measurements of the total cross section for top-antitop quark production

Abstract

We present a determination of the strong coupling constant ${\alpha }_s(m_Z)$ using inclusive top-quark pair production cross section measurements performed at the LHC and at the Tevatron. Following a procedure first applied by the CMS collaboration, we extract individual values of ${\alpha }_s(m_Z)$ from measurements by different experiments at several centre-of-mass energies, using QCD predictions complete in NNLO perturbation theory, supplemented with NNLL approximations to all orders, and suitable sets of parton distribution functions. The determinations are then combined using a likelihood-based approach, where special emphasis is put on a consistent treatment of theoretical uncertainties and of correlations between various sources of systematic uncertainties. Our final combined result is ${\alpha }_s(m_Z)=0.1177_{-0.0036}^{+0.0034}$.

23 pages, 4 figures; v2 adds clarifications and further analysis details

References in corpus (9)

• LHAPDF6: parton density access in the LHC precision era
• Parton distributions in the LHC era: MMHT 2014 PDFs
• The global electroweak fit at NNLO and prospects for the LHC and ILC
• The five-loop beta function of Yang-Mills theory with fermions
• Thrust at N^3LL with Power Corrections and a Precision Global Fit for alphas(mZ)
• Threshold Resummation for Top-Pair Hadroproduction to Next-to-Next-to-Leading Log
• The strong coupling from a nonperturbative determination of the $\Lambda$ parameter in three-flavor QCD
• A Precise Determination of ${\alpha }_s$ from the C-parameter Distribution
• An extensive survey of the estimation of uncertainties from missing higher orders in perturbative calculations

Cited by in corpus (3)

• Top-pair production at the LHC with MiNNLO${}_{\mathrm{PS}}$
• Precision physics with inclusive QCD processes
• $J/\psi$ meson production in association with an open charm hadron at the LHC: A reappraisal