Heidelberg 2022 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 34: Top Quarks: Properties -2

T 34.5: Vortrag

Dienstag, 22. März 2022, 17:15–17:30, T-H19

Search for flavour-changing photon interactions in top-quark production and decay at the ATLAS experiment — Tomas Dado, Johannes Erdmann, Benedikt Gocke, •Florian Mausolf, Olaf Nackenhorst, and Björn Wendland — TU Dortmund University, Department of Physics

In the Standard Model (SM) of particle physics, flavour-changing neutral currents (FCNC) are strongly suppressed, but several theories beyond the SM predict FCNC with much higher rates. In this talk, a search for flavour-changing photon interactions in top-quark production and decay is presented. Proton-proton-collision data corresponding to an integrated luminosity of 139 fb⁻¹ are analysed which were taken with the ATLAS detector at a centre-of-mass energy of 13 TeV. It is separately searched for interactions involving the top quark, the up quark and the photon as well as for interactions of the top quark, the charm quark and the photon. Events with one photon, one b-tagged jet, one electron or one muon, and a minimum amount of missing transverse momentum are selected. Contributions from events with objects mis-reconstructed as photons are estimated using data-driven methods. Multiclass deep neural networks are used to separate the signal from the background. The analysis strategy is presented and upper limits on the strength of the FCNC couplings are set.