Measurement of the tt¯ production cross-section and lepton differential distributions in eμ dilepton events from pp collisions at √s=13TeV with the ATLAS detector

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Aad, G 
Abbott, B 
Abbott, DC 
Abud, AA 
Abeling, K 

The inclusive top quark pair (tt¯) production cross-section σtt¯ has been measured in protonproton collisions at s=13 TeV, using 36.1 fb−1 of data collected in 2015$-$16 by the ATLAS experiment at the LHC. Using events with an opposite-charge eμ pair and b-tagged jets, the cross-section is measured to be: \begin{equation}\nonumber \sigma_{t\bar{t}} = 826.4 \pm 3.6,\mathrm{(stat)}
\pm 11.5,\mathrm{(syst)}\ \pm 15.7,\mathrm{(lumi)}\ \pm 1.9,\mathrm{(beam)},\mathrm{pb}, \end{equation} where the uncertainties reflect the limited size of the data sample, experimental and theoretical systematic effects, the integrated luminosity, and the LHC beam energy, giving a total uncertainty of 2.4%. The result is consistent with theoretical QCD calculations at next-to-next-to-leading order. It is used to determine the top quark pole mass via the dependence of the predicted cross-section on mtpole, giving mtpole=173.1−2.1+2.0 GeV. It is also combined with measurements at s=7 TeV and s=8 TeV to derive ratios and double ratios of tt¯ and Z cross-sections at different energies. The same event sample is used to measure absolute and normalised differential cross-sections as functions of single-lepton and dilepton kinematic variables, and the results compared with predictions from various Monte Carlo event generators.

hep-ex, hep-ex
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European Physical Journal C
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Springer Science and Business Media LLC
Science and Technology Facilities Council (ST/N000234/1)