Karlsruhe 2024 – scientific programme

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T: Fachverband Teilchenphysik

T 74: Top physics 3 (single top)

T 74.3: Talk

Wednesday, March 6, 2024, 16:30–16:45, Geb. 30.95: Audimax

Measurement of top quark involved CKM matrix elements in single top-quark t-channel processes — Tomas Dado, •Benedikt Gocke, and Kevin Kröninger — Technische Universität Dortmund, AG Kröninger

Measuring top quark properties is one of the main purposes of the ATLAS experiment at the LHC. Since the top quark is the heaviest quark and thus decays before it hadronises, it can be seen as a quasi free quark. Therefore, its properties and especially its couplings are crucial to test the Standard model.

In general, all flavour-changing quark couplings are described by the Cabbibo-Kobayashi-Maskawa (CKM) matrix. There are no theoretical predictions for any CKM matrix elements. Thus, these need to be measured. For the small CKM matrix-elements Vts and Vtd, a measurement is especially challenging.

Single top-quark t-channel cross section measurements can be used to extract V_tb. In this talk, the CKM interpretation of the single top-quark t-channel cross-section measurement at √s=13 TeV with the ATLAS experiment is presented. For this purpose, all possible top quark production and decay vertices are considered. The measurement exploits the full Run2 dataset corresponding to an integrated luminosity of 140 fb⁻¹. For the first time, two-dimensional profile-likelihood scans are used to also set limits on V_td and V_ts.

Keywords: single top