SMuK 2023 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 58: Other Exp., tt

T 58.3: Vortrag

Mittwoch, 22. März 2023, 16:20–16:35, HSZ/0103

Measurement of the top-quark pair to Z-boson production cross-section ratio at a centre-of-mass energy of 13.6 TeV with the ATLAS detector — •Donna Maria Mattern, Tomáš Dado, and Kevin Kröninger — TU Dortmund, Fakultät Physik

The ratio of the top-quark-pair production cross-section to the Z-boson production cross-section is sensitive to the gluon-to-quark ratio of parton distribution functions and other parameters that allow to study the Standard Model, such as the strong coupling constant and the top-quark mass.

A measurement of the top-quark-pair and Z-boson production cross-section, as well as the cross-section ratio, using data collected in proton-proton collisions in 2022 during the early Run 3 of the Large Hadron Collider (LHC) at a center-of-mass energy of 13.6 TeV with the ATLAS experiment, corresponding to an integrated luminosity of 1.2 fb⁻¹, is presented.

Events with an oppositely charged electron-muon pair, as well as b-tagged jets, are used for the top-quark-pair production, while same-flavor dileptonic events are used for the Z-boson production cross-section measurement.

The probability to reconstruct and tag a b-jet is measured in-situ. A large cancellation of the luminosity uncertainty is achieved in the ratio, while this uncertainty is otherwise dominant in cross-section measurements in the early stages of the Run 3 of the LHC. This early result at the new center-of-mass energy at the LHC also serves to validate data quality, hardware and software updates.