Dortmund 2021 – wissenschaftliches Programm
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T: Fachverband Teilchenphysik
T 79: Top quark production III
T 79.8: Vortrag
Donnerstag, 18. März 2021, 17:45–18:00, Td
Evidence for tttt production in same-sign dilepton and multilepton final states at the LHC with the ATLAS detector using the full Run-2 dataset — Vakhtang Ananiashvili1, •Ö. Oğul Öncel1, Niklas Werner Schwan1, and Markus Cristinziani2 — 1Physikalisches Institut, Universität Bonn — 2Center for Particle Physics Siegen, Experimentelle Teilchenphysik, Universität Siegen
Production of tttt in proton–proton collisions is a rare process predicted by the Standard Model with an expected cross section at √s=13 TeV of around 0.01 pb. Many BSM theories, such as Top Compositeness and 2HDM, predict an enhancement of the tttt cross section. In addition, tttt can also be used to measure the top-quark Yukawa coupling, another important quantity for probing new physics.
The recently established evidence for this process in the same-sign dilepton and multilepton channels using ATLAS data collected at the LHC during 2015–2018 with 139.4 fb−1 integrated luminosity and at a centre-of-mass energy of 13 TeV, is presented. The main challenges are the small cross section, irreducible backgrounds from the ttZ, ttH, and ttW processes, as well as sizeable backgrounds due to charge mis-identification and photon conversion.