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arXiv · 1911.13204

Measurement of the top quark pair production cross section in dilepton final states containing one $τ$ lepton in pp collisions at $\sqrt{s} =$ 13 TeV

CMS Collaboration
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Abstract

The cross section of top quark pair production is measured in the $\mathrm{t\bar{t}}$ $\to$ $(\ellν_{\ell})(τ_\mathrm{h}ν_τ)\mathrm{b\bar{b}}$ final state, where $τ_\mathrm{h}$ refers to the hadronic decays of the $τ$ lepton, and $\ell$ is either an electron or a muon. The data sample corresponds to an integrated luminosity of 35.9 fb$^{-1}$ collected in proton-proton collisions at $\sqrt{s} =$ 13 TeV with the CMS detector. The measured cross section is $σ_{\mathrm{t\bar{t}}} =$ 781 $\pm$ 7 (stat) $\pm$ 62 (syst) $\pm$ 20 (lum) pb, and the ratio of the partial width $Γ($t $\to$ $τν_τ$b) to the total decay width of the top quark is measured to be 0.1050 $\pm$ 0.0009 (stat) $\pm$ 0.0071 (syst). This is the first measurement of the $\mathrm{t\bar{t}}$ production cross section in proton-proton collisions at $\sqrt{s} =$ 13 TeV that explicitly includes $τ$ leptons. The ratio of the cross sections in the $\ellτ_\mathrm{h}$ and $\ell\ell$ final states yields a value $R_{\ellτ_\mathrm{h}/\ell\ell} =$ 0.973 $\pm$ 0.009 (stat) $\pm$ 0.066 (syst), consistent with lepton universality.

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CMS Collaboration. 2020-03-05. Measurement of the top quark pair production cross section in dilepton final states containing one $τ$ lepton in pp collisions at $\sqrt{s} =$ 13 TeV. https://doi.org/10.1007/jhep02(2020)191

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