Bonn 2020 – scientific programme
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T: Fachverband Teilchenphysik
T 65: Top quarks: differential cross sections
T 65.1: Talk
Wednesday, April 1, 2020, 16:30–16:45, H-HS VIII
Top-antitop energy asymmetry in jet-associated top-quark pair production at ATLAS — •Alexander Basan, Peter Berta, Lucia Masetti, and Eftychia Tzovara — Johannes Gutenberg University Mainz
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 like massive color-octet states, extra dimensions, flavor violating gauge bosons and axigluons. Within the framework of effective field theories (EFT), 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 strategy in lepton+jets events with a high pT hadronically decaying top quark at ATLAS with a center of mass energy of √s=13 TeV as well as expected sensitivities to the Wilson coefficients.