Dortmund 2021 – scientific programme

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T: Fachverband Teilchenphysik

T 8: Top quark production I

T 8.6: Talk

Monday, March 15, 2021, 17:15–17:30, Th

Measurement of the inclusive production cross sections of a top-quark pair in association with a Z boson at √s=13 TeV in final states with three leptons using deep neural nets with the ATLAS detector — •Steffen Korn, Arnulf Quadt, Elizaveta Shabalina, and Knut Zoch — II. Physikalisches Institut, Georg-August-Universität Göttingen

Through the associated production of the ttZ process, the strength and structure of the coupling of the top quark and the Z boson can be measured which provides sensitivity to the top quark’s weak isospin in the Standard Model (SM). The measurement of this fundamental parameter of the SM also serves as a probe to new physics beyond the SM. The process was first observed by CMS and first measured by ATLAS at √s=8 TeV by considering ttW and ttZ processes simultaneously, and later measured with increased precision at √s=13 TeV by both experiments. The effect of deep neural networks (DNN) on the sensitivity of a refined analysis using 139 fb⁻¹ is investigated and presented within a measurement of the inclusive cross section in ttZ final states. The analysis selects event with three charged leptons in proton-proton collisions data, taken between 2015 and 2018 with the ATLAS detector.