Erlangen 2026 – scientific programme
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T: Fachverband Teilchenphysik
T 23: Top Physics I
T 23.6: Talk
Tuesday, March 17, 2026, 17:30–17:45, KH 00.011
Flavour Changing Neutral Current decays of the top quark to a Higgs boson and a charm or up quark with the ATLAS experiment — Diptaparna Biswas, Carolina Costa, Markus Cristinziani, Carmen Diez Pardos, Ivor Fleck, Gabriel Gomes, Jan Joachim Hahn, Nikolaos Kamaras, Vadim Kostyukhin, Nils Benedikt Krengel, Austin Olson, •Inês Pinto, Sebastian Rentschler, Elisabeth Schopf, Katharina Voss, Wolfgang Walkowiak, and Adam Warnerbring — Experimentelle Teilchenphysik, Center for Particle Physics Siegen, Universität Siegen
Top-quarks can decay to lighter quarks with the same charge by emitting a neutral boson in processes called Flavour Changing Neutral Current (FCNC). These are forbidden at the lowest order, and highly suppressed at higher orders, by the Glashow–Iliopoulos–Maiani mechanism.
We aim to search for FCNC decays of a top quark to a Higgs boson, and either a charm or an up quark, with data collected by the ATLAS detector during Run 2 and the ongoing Run 3 of the LHC. These decay modes are extremely rare, with expected branching ratios of about 10−15 for t→ Hc and 10−17 for t→ Hu, far beyond the sensitivity of current detectors. As such, observing these decays at a significant rate would be a clear indication of New Physics. The search will aim to exploit the highest branching ratio decay mode of the Higgs boson, H→ bb, taking advantage of the latest machine learning developments in jet flavour tagging in the ATLAS experiment.
Keywords: FCNC, Top Quark, Higgs Boson, ATLAS Experiment