SMuK 2023 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 3: Top I

T 3.3: Vortrag

Montag, 20. März 2023, 17:00–17:15, HSZ/0401

Measurement of SMEFT parameters in tt+γ using Run 2 data with the ATLAS experiment — •Jan Joachim Hahn¹, Binish Batool¹, Beatrice Cervato¹, Markus Cristinziani¹, Carmen Diez Pardos¹, Ivor Fleck¹, Arpan Ghosal¹, Gabriel Gomes¹, Vadim Kostyukhin¹, Buddhadeb Mondal¹, Amartya Rej¹, Katharina Voss¹, Wolfgang Walkowiak¹, and Tongbin Zhao^1,2 — ¹Center for Particle Physics Siegen, Experimentelle Teilchenphysik, Universität Siegen — ²Shandong University, China

In the Standard Model Effective Field Theory (SMEFT), the effects of physics phenomena beyond the Standard Model (SM) are modelled via higher dimension operators. Measurements of sensitive processes can be used to constrain the coefficients of operators that contribute to a process. The top quark is the heaviest known particle and the only quark that decays before hadronisation. It is expected to play a relevant role in many models of physics beyond the SM given its large mass. Final states including photons are sensitive to modifications in the electroweak sector, changing the photon energy spectrum. This talk will focus on a interpretation of the ongoing ttγ cross section measurement in terms of SMEFT. To constrain several EFT operators, ttγ events decaying semileptonically are studied. The study is performed using the full Run 2 data set collected by the ATLAS experiment corrosponding to 139 fb⁻¹ at √s=13 TeV.