Heidelberg 2022 – wissenschaftliches Programm
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T: Fachverband Teilchenphysik
T 60: Top Quarks: Decay and CP Violation and Mixing Angles
T 60.4: Vortrag
Mittwoch, 23. März 2022, 17:00–17:15, T-H19
Search for flavour-changing neutral current couplings between the top-quark and the Higgs boson in the H → bb decay channel and the tri-lepton final state with the ATLAS detector at the LHC — •Oliver Thielmann1, Geoffrey Gilles4, Wolfgang Wagner1, Marvin Emin Geyik1, Dominic Hirschbühl1, Kyungeon Choi2, Frederic Deliot3, Charles Michael Grant5, Paul Jackson5, Peter Onyisi2, Abhishek Sharma6, and Marc Tost2 — 1Bergische Universität Wuppertal — 2Austin — 3Saclay CEA — 4Nikhef — 5Adelaide — 6Columbia
A search for flavour-changing neutral current (FCNC) couplings between the top-quark and the Higgs boson in the H → bb decay channel and the tri-lepton final state 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 different final states, characterised by the number of isolated electrons or muons, missing transverse energy and the number of jets where either three (for H → bb) or one (for tri-lepton final state) 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, interpreted in the context of an effective field theory for FCNC, are presented, where additional exclusion limits on the qtH effective coupling are derived.