Measurements of the charge asymmetry in top-quark pair production in the dilepton final state at $\sqrt{s}=8$ TeV with the ATLAS detector

Abstract

Measurements of the top--antitop quark pair production charge asymmetry in the dilepton channel, characterized by two high-$p_{\mathrm{T}}$ leptons (electrons or muons), are presented using data corresponding to an integrated luminosity of $20.3$ ${\text{fb}}^{-1}$ from $pp$ collisions at a center-of-mass energy of $\sqrt{s}=8$ 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 $t\bar{t}$ system are performed both in the full phase space and in a fiducial phase space closely matching the detector acceptance. Two observables are studied: $A_{\text{C}}^{\ell \ell }$ based on the selected leptons and $A_{\text{C}}^{t\bar{t}}$ based on the reconstructed $t\bar{t}$ final state. The inclusive asymmetries are measured in the full phase space to be $A_{\text{C}}^{\ell \ell }=0.008\pm 0.006$ and $A_{\text{C}}^{t\bar{t}}=0.021\pm 0.016$, which are in agreement with the Standard Model predictions of $A_{\text{C}}^{\ell \ell }=0.0064\pm 0.0003$ and $A_{\text{C}}^{t\bar{t}}=0.0111\pm 0.0004$.

29 pages plus author list + cover pages (45 pages total), 8 figures, 4 tables, published in Physical Review D, All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/TOPQ-2015-08/

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