Measurement of the Charge Asymmetry in Top-Quark Pair Production in the Lepton-Plus-Jets Final State in pp Collision Data at √s = 8 TeV With the ATLAS Detector

Abstract

This paper reports inclusive and differential measurements of the tt¯tt¯ charge asymmetry ACAC in 20.3 fb−120.3 fb−1 of s√=8 TeVs=8 TeV pppp collisions recorded by the ATLAS experiment at the Large Hadron Collider at CERN. Three differential measurements are performed as a function of the invariant mass, transverse momentum and longitudinal boost of the tt¯tt¯ system. The tt¯tt¯ pairs are selected in the single-lepton channels (e or μμ ) with at least four jets, and a likelihood fit is used to reconstruct the tt¯tt¯ event kinematics. A Bayesian unfolding procedure is performed to infer the asymmetry at parton level from the observed data distribution. The inclusive tt¯tt¯ charge asymmetry is measured to be AC=0.009±0.005AC=0.009±0.005 (stat. ++ syst.). The inclusive and differential measurements are compatible with the values predicted by the Standard Model.