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T: Fachverband Teilchenphysik

T 55: Search for new particles III

T 55.10: Vortrag

Mittwoch, 1. April 2020, 18:45–19:00, H-HS XVI

Search for FCNC coupling between the top quark and the Higgs boson in the H→ bb decay channel — •Arunika Sahu for the ATLAS collaboration — Bergische Universitaet Wuppertal

Processes involving flavour-changing neutral currents (FCNC) are highly suppressed in the top-quark sector. Any observations of such processes would therefore be a signal for physics beyond the Standard Model. The FCNC contributions in pp→tH process comes from qtH and qtg interactions at leading order. We assume the qtg coupling contributions to be negligible and consider only qtH coupling contributions. In the presented analysis, we search for the pp→tH process, involving ctH and utH FCNC vertices. Final states are considered in which the top quark decays semi-leptonically and the Higgs boson decays into a bb pair. A serious background to tH(H→ bb) are events featuring two b-jets from top decays and one or two heavy flavour jets from gluon splitting. tt with 3 b-tagged jets are expected to be underestimated. We develop a data-driven approach to correct this tt+ Heavy Flavor underestimation in our signal regions. This challenging tt+bb (cc) background is estimated via dedicated control regions. Neural networks are employed to separate signal and background events in the signal region.