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Precision determination of the strong coupling constant within a global PDF analysis: NNPDF Collaboration.

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Ball, Richard D 
Carrazza, Stefano 
Debbio, Luigi Del 
Kassabov, Zahari 


We present a determination of the strong coupling constant α s ( m Z ) based on the NNPDF3.1 determination of parton distributions, which for the first time includes constraints from jet production, top-quark pair differential distributions, and the Z p T distributions using exact NNLO theory. Our result is based on a novel extension of the NNPDF methodology - the correlated replica method - which allows for a simultaneous determination of α s and the PDFs with all correlations between them fully taken into account. We study in detail all relevant sources of experimental, methodological and theoretical uncertainty. At NNLO we find α s ( m Z ) = 0.1185 ± 0 . 0005 (exp) ± 0 . 0001 (meth) , showing that methodological uncertainties are negligible. We conservatively estimate the theoretical uncertainty due to missing higher order QCD corrections (N 3 LO and beyond) from half the shift between the NLO and NNLO α s values, finding Δ α s th = 0.0011 .



hep-ph, hep-ph, hep-ex

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Eur Phys J C Part Fields

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Springer Science and Business Media LLC
Science and Technology Facilities Council (ST/J000434/1)
Royal Society (DH150088)
Royal Society (RGF/EA/180148)
European Research Council (683211)