Heidelberg 2022 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

T: Fachverband Teilchenphysik

T 6: Top Quarks: Production (Exp.) 1

T 6.9: Vortrag

Montag, 21. März 2022, 18:15–18:30, T-H19

Search for flavour-changing neutral-current interactions of a top quark and a gluon in pp collisions at √s=13 TeV with the ATLAS detector — •Wolfgang Wagner, Gunnar Jäkel, and Dominic Hirschbühl — Bergische Universität Wuppertal

In the standard model, flavour-changing neutral currents (FCNCs) are strongly suppressed, in particular in the top-quark sector. Any observation of top-quark-related FCNCs will thus be a clear sign of physics beyond the standard model. A search is presented for the production of a single top quark via left-handed flavour-changing neutral-current (FCNC) interactions of a top quark, a gluon and an up or charm quark. Two production processes are considered: u+g→ t and c+g→ t. The analysis is based on proton–proton collision data taken at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC. The data set corresponds to an integrated luminosity of 139 fb⁻¹. Events with exactly one electron or one muon, exactly one b-tagged jet and missing transverse momentum are selected, resembling the decay products of a singly produced top quark. Neural networks based on kinematic variables differentiate between events from the two signal processes and events from background processes. The measured data are consistent with the background-only hypothesis, and limits are set on the production cross-sections of the signal processes. Based on the framework of an effective field theory, the cross-section limits are translated into limits on the strengths of the tug and tcg couplings occurring in the theory.