Evidence for the charge asymmetry in pp → $$ t\overline{t} $$ production at $$ \sqrt{s} $$ = 13 TeV with the ATLAS detector

Abstract Inclusive and differential measurements of the top–antitop ( $$ t\overline{t} $$ t t ¯ ) charge asymmetry $$ {A}_{\textrm{C}}^{t\overline{t}} $$ A C t t ¯ and the leptonic asymmetry $$ {A}_{\textrm{C}}^{\ell \overline{\ell}} $$ A C ℓ ℓ ¯ are presented in proton–proton collisions at $$ \sqrt{s} $$ s = 13 TeV recorded by the ATLAS experiment at the CERN Large Hadron Collider. The measurement uses the complete Run 2 dataset, corresponding to an integrated luminosity of 139 fb−1, combines data in the single-lepton and dilepton channels, and employs reconstruction techniques adapted to both the resolved and boosted topologies. A Bayesian unfolding procedure is performed to correct for detector resolution and acceptance effects. The combined inclusive $$ t\overline{t} $$ t t ¯ charge asymmetry is measured to be $$ {A}_{\textrm{C}}^{t\overline{t}} $$ A C t t ¯ = 0.0068 ± 0.0015, which differs from zero by 4.7 standard deviations. Differential measurements are performed as a function of the invariant mass, transverse momentum and longitudinal boost of the $$ t\overline{t} $$ t t ¯ system. Both the inclusive and differential measurements are found to be compatible with the Standard Model predictions, at next-to-next-to-leading order in quantum chromodynamics perturbation theory with next-to-leading-order electroweak corrections. The measurements are interpreted in the framework of the Standard Model effective field theory, placing competitive bounds on several Wilson coefficients.

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