$a_S$ extraction from inclusive W and Z cross sections in pp collisions at the LHC
July 22, 2019
September 13, 2019
Twenty-eight different measurements of inclusive W±and Z cross sections in pp collisions at theLHC are compared to the corresponding theoretical predictions, at NNLO accuracy in perturba-tive QCD including NLO electroweak corrections, in order to extract the QCD coupling at theZ pole,αs(mZ). The theoretical cross sections are computed for four different parton distribution functions (PDFs): CT14, HERAPDF 2.0, MMHT14, and NNPDF 3.0. The calculated cross sections reproduce well the data within experimental and theoretical uncertainties. A linear fit of the αs dependence of the theoretical cross sections is used to extract the αs(mZ)value that best reproduces the measured cross sections. The 28αs(mZ)values extracted from each measurement are combined into a single result by properly taking into account their uncertainties and correlations. The following NNLO values of the QCD coupling for each one of the PDF sets are obtained:αs(mZ) =0.1181±0.0016 (CT14), 0.1209±0.0015 (MMHT14), and 0.1163±0.0019(NNPDF 3.0), with a final uncertainty at the 1.5% level, in good agreement with the αs(mZ)world average.
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