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T: Fachverband Teilchenphysik
T 34: Top-Quarks: Eigenschaften I
T 34.7: Vortrag
Dienstag, 20. März 2018, 18:00–18:15, Z6 - SR 1.002
Top-antitop energy asymmetry in jet-associated top-quark pair production at ATLAS — •Alexander Basan, Peter Berta, Sabrina Groh, Melanie Schepp, and Lucia Masetti — Intitute of Physics, Johannes Gutenberg University Mainz
The top quark is particularly well suited to probe the standard model and many extensions thereof at the electroweak symmetry-breaking scale and beyond. Specifically, the charge asymmetry in tt events can provide sensitive probes for many models beyond the standard model including massive color-octet states, extra dimensions, flavor violating gauge bosons and axigluons.
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 of the tt energy asymmetry in the lepton+jets channel at ATLAS with a center of mass energy of √s=13 TeV. Additionally to top quarks produced close to threshold, boosted topologies are studied separately to estimate the improvement in sensitivity due to the different kinematic region and reduced combinatorial background.