Heidelberg 2022 – wissenschaftliches Programm
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T: Fachverband Teilchenphysik
T 34: Top Quarks: Properties -2
T 34.2: Vortrag
Dienstag, 22. März 2022, 16:30–16:45, T-H19
Top-antitop energy asymmetry in jet-associated top-quark pair production at ATLAS — •Alexander Basan1, Asma Hadef1, Jessica Höfner1, Lucia Masetti1, Eftychia Tzovara1, and Susanne Westhoff2 — 1Universität Mainz — 2Universität Heidelberg
The top quark is particularly well suited to probe the standard model (SM) and many extensions thereof at the electroweak symmetry-breaking scale and beyond.
At hadron colliders, the tt production is symmetric at leading order perturbation theory under the exchange of the top- and anti-top-quark, while interferences at higher orders create an asymmetry. This charge asymmetry can provide sensitive probes for many models beyond the standard model. Within the framework of standard model effective field theories (SMEFT), the charge asymmetry is especially sensitive to four-quark operators and one operator that modifies the top-gluon interaction.
In inclusive jet-associated top-quark pair production the asymmetry arises already at leading order in quark-gluon interactions. Furthermore, the ttj final states allow the definition of a new observable, the energy asymmetry, expressed in terms of the distribution of the energy difference Et − Et.
This talk presents the measurement in lepton+jets events with a high pT hadronically decaying top quark at ATLAS with a centre of mass energy of √s=13 TeV as well as limits on the Wilson coefficients of four-quark operators within the SMEFT framework.