| We present a new measurement of the inclusive forward-backward tt¯ production asymmetry and its mass dependence. The measurements are performed with data corresponding to an integrated luminosity of L = 5.3 fb−1 of pp¯ collisions at s = 1.96 TeV, recorded with the CDF II Detector at the Fermilab Tevatron. Significant inclusive asymmetries are observed in both the laboratory frame and the tt¯ rest frame, and in both cases are found to be consistent with CP conservation under interchange of t and t¯. In the tt¯ rest frame, the asymmetry is observed to increase with the invariant mass, Mtt¯, of the tt¯ system. Fully corrected parton-level asymmetries are derived in two regions of Mtt¯, and the asymmetry is found to be most significant at large Mtt¯ . For Mtt¯ ≥ 450 GeV/ c2, the parton-level asymmetry in the tt¯ rest frame is Att¯ = 0.475 ± 0.114 compared to a next-to-leading order QCD prediction of 0.088 ± 0.013. |
