Karlsruhe 2024 – scientific programme
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T: Fachverband Teilchenphysik
T 23: Top physics 1
T 23.9: Talk
Monday, March 4, 2024, 18:00–18:15, Geb. 30.95: Audimax
Search for charged lepton flavour violation in top-quark production and decay with the ATLAS experiment — Diptaparna Biswas1, Beatrice Cervato1, Markus Cristinziani1, Carmen Diez Pardos1, Ivor Fleck1, Arpan Ghosal1, •Gabriel Gomes1, Jan Joachim Hahn1, Vadim Kostyukhin1, Nils Krengel1, Buddhadeb Mondal1, Stefanie Müller1, Katharina Voss1, Wolfgang Walkowiak1, Adam Warnerbring1, and Tongbin Zhao1,2 — 1Experimentelle Teilchenphysik, Center for Particle Physics Siegen, Universität Siegen — 2Shandong University, China
In the Standard Model with massless neutrinos, the flavour of charged leptons cannot be altered in weak interactions. However, the observed neutrino oscillations allow for charged lepton flavour violating processes, even though suppressed much below our current experimental sensitivity. Hence, experimental evidence of such rare processes would provide signs of new physics beyond the SM.
Investigations targeting a direct search for charged lepton flavour violation will be presented using proton–proton collision data collected by the ATLAS detector between 2015 and 2018 at √s = 13 TeV. In tt pair production, decays of a top quark into an electron–muon pair and an up-type quark are examined as well as single top-quark production in association with an electron–muon pair. In the tt case, the final state of interest is obtained when the SM top-originated W decays hadronically, and similarly for the single top production. A multivariate discriminant, namely a boosted decision tree, is implemented and optimised for signal discrimination purposes.
Keywords: Charged lepton flavour violation; Top quark; ATLAS; Boosted Decision Trees