Dortmund 2021 – scientific programme

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T: Fachverband Teilchenphysik

T 52: Top quark decay and top properties II

T 52.8: Talk

Wednesday, March 17, 2021, 17:45–18:00, Tb

Search for flavour-changing neutral current couplings between the top-quark and the Higgs boson in the H → bb decay channel with the ATLAS detector at the LHC — •Oliver Thielmann, Geoffrey Gilles, and Wolfgang Wagner — Bergische Universität Wuppertal

A search for flavour-changing neutral current (FCNC) couplings between the top-quark and the Higgs boson in the H → bb decay channel is presented. The search for FCNC couplings in the top-quark-Higgs-boson sector is a promising search for a theory beyond the SM. Proton-proton collision data produced by the LHC at a centre-of-mass energy of √s = 13 TeV and collected by the ATLAS experiment during 2015, 2016, 2017 and 2018, and corresponding to an integrated luminosity of 139 fb⁻1, are used. Data is analysed in three different final states, characterised by one isolated electron or muon, missing transverse energy and three, four or more than five jets where three of them are identified as b-jets. A machine learning analysis based on neural networks is conducted to improve the discrimination between the signal and the backgrounds. Preliminary results on the expected signal cross section exclusion limits are derived using the CLs method. Further interpretation is performed in the context of an effective field theory for FCNC where additional exclusion limits on the qtH effective coupling are derived.