2023

Inclusive and differential measurements of the top-antitop (t-t) charge asymmetry

At-t

C and the leptonic asymmetry A'-'

C are presented in proton-proton collisions at p 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-t charge asymmetry is measured to be At-t

C = 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-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.