Inclusive and differential measurement of the charge asymmetry in $t\bar{t}$ events at 13 TeV with the ATLAS detector

A measurement of the top-antitop ($t\bar t$) charge asymmetry $A_{\text{C}}$ is presented using data corresponding to an integrated luminosity of 139 fb$^{-1}$ of $\sqrt{s} = 13$ TeV of $pp$ collisions recorded by the ATLAS experiment at the Large Hadron Collider, CERN. The measurement is performed in the single-lepton channel ($e$ or $\mu$) combining both the resolved and boosted topologies of top quark decays. A Bayesian unfolding procedure is used to infer the asymmetry at parton level, correcting for detector resolution and acceptance effects. The inclusive $t\bar t$ charge asymmetry is measured as $A_{\text{C}} = 0.0060 \pm 0.0015 \textrm{(stat+syst.)}$, which differs from zero by 4 standard deviations. Differential measurements are performed as a function of the invariant mass and longitudinal boost of the $t\bar t$ system. Both inclusive and differential measurements are found to be compatible with the Standard Model predictions, at NNLO in perturbation theory with NLO electroweak corrections.