Measurements of the charge asymmetry in top-quark pair production in the dilepton final state at √s=8 TeV with the ATLAS detector

Abstract

Measurements of the top–antitop quark pair production charge asymmetry in the dilepton channel, characterized by two high-pT leptons (electrons or muons), are presented using data corresponding to an integrated luminosity of 20.3 fb−1 from pp collisions at a center-of-mass energy √ s = 8 TeV collected with the ATLAS detector at the Large Hadron Collider at CERN. Inclusive and differential measurements as a function of the invariant mass, transverse momentum, and longitudinal boost of the tt¯ system are performed both in the full phase space and in a fiducial phase space closely matching the detector acceptance. Two observables are studied: A C based on the selected leptons and A tt¯ C based on the reconstructed tt¯ final state. The inclusive asymmetries are measured in the full phase space to be A C = 0.008 ± 0.006 and A tt¯ C= 0.021 ± 0.016, which are in agreement with the Standard Model predictions of A `` C = 0.0064 ± 0.0003 and A tt¯ C = 0.0111 ± 0.0004.