SMuK 2023 – wissenschaftliches Programm
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T: Fachverband Teilchenphysik
T 81: Single Top, Top Properties
T 81.5: Vortrag
Mittwoch, 22. März 2023, 18:30–18:45, HSZ/0103
Measurements of top-quark pair spin correlation in the ℓ + jets channel using the ATLAS experiment — •Oleksandr Burlayenko, A. Knue, and Z. Rurikova for the ATLAS collaboration — University of Freiburg
The top quark is the heaviest known fundamental particle and has a lifetime of O(10−25s). This lifetime is shorter than the quantum chromodynamic (QCD) hadronization time scale 1/ΛQCD≈ 10−24s, and much shorter than the spin decorrelation time scale mt/ΛQCD2≈10−21s. This gives an opportunity to study the spin properties of a bare quark, as top-quark spin information is preserved in the angular distribution of its decay products.
The Standard Model predicts the tt pairs to have correlated spins. The degree of this correlation is sensitive to the production mechanism. The most recent measurement performed by ATLAS uses 13 TeV data in the dilepton channel.
This work presents ongoing studies of the tt spin correlation in the ℓ + jet channel at √s=13 TeV. While this channel provides a larger dataset to study, the analyzing power is reduced compared to the dilepton channel.
To improve the event reconstruction, machine learning techniques are employed and non-reconstructable events are removed. Studies of various observables on particle- and detector-level measured inclusively and as a function of mass of the tt system will be presented. In addition the impact of systematic uncertainties on these observables will be studied.