Charge asymmetry in top-pair production with the ATLAS detector

TL;DR

This paper reports a measurement of the top-quark charge asymmetry using ATLAS Run 2 data, revealing a significant excess over the Standard Model prediction at 4.7 standard deviations.

Contribution

First measurement of top-quark charge asymmetry in both inclusive and differential forms using full Run 2 ATLAS data, with Bayesian unfolding to correct detector effects.

Findings

Observed a 4.7 sigma excess over zero asymmetry hypothesis.

Measured leptonic charge asymmetry consistent with Standard Model.

Combined results from single-lepton and dilepton channels.

Abstract

Measurement of the inclusive and differential top-quark charge asymmetry is carried out using full Run 2 data from proton-proton collisions at a center-of-mass energy of $13$ TeV collected by the ATLAS detector. The single-lepton and dilepton $t\bar{t}$ decay channels are combined. Distorting detector effects are removed using fully Bayesian unfolding. In the dilepton decay channel, the leptonic charge asymmetry is determined. Results from the measurements are compared with the Standard Model prediction. The excess of charge asymmetry from zero charge-asymmetry hypothesis at the level of $4.7$ standard deviations is observed.