Precision determination of the strong coupling constant within a global PDF analysis: NNPDF Collaboration
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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 Zp T distributions using exact NNLO theory. Our result is based on a novel extension of the NNPDF methodology – th e 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 Δαsth=0.0011.
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1434-6052
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Royal Society (DH150088)
Royal Society (RGF/EA/180148)