Publications associated with Particle Theory

Determination of the strong coupling constant αsmZ from measurements of the total cross section for top-antitop-quark production.

The European physical journal. C, Particles and fields 77 (2017) 778-

T Klijnsma, S Bethke, G Dissertori, GP Salam

We present a determination of the strong coupling constant αsmZ 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 αsmZ 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 αsmZ=0.1177-0.0036+0.0034 .

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