Speaker
Description
We present a simultaneous determination of the strong coupling constant $\alpha_s(m_Z)$ and the top-quark mass $m_t$ within a global PDF analysis based on the public NNPDF framework. We consider a wide range of $t\bar{t}$ measurements, including both single- and double-differential observables, computed at NNLO QCD accuracy, and analyse their individual as well as combined impact on the joint $\alpha_s, m_t$ parameter space, while accounting for PDF evolution up to (approximate) N3LO QCD accuracy with QED corrections. Unique to our analysis are the inclusion of, first, toponium contributions around the $t\bar{t}$ threshold, second, state-of-the-art constraints on $\alpha_s$ from the lattice, and finally, a detailed sensitivity study of various ATLAS and CMS measurements. The last point will demonstrate explicitly how their combination requires one to refit the PDFs in order to correctly correlate uncertainties.
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