Abstract
We present a new measurement of the inclusive forward-backward t-tbar
production asymmetry and its rapidity and mass dependence. The measurements are
performed with 5.3 fb^-1 of p-pbar collisions at s = 1.96 TeV,
recorded with CDF II at the Fermilab Tevatron. Significant inclusive
asymmetries are observed in the laboratory and t-tbar rest frame, and are
consistent with CP conservation under interchange of t and tbar. In the t-tbar
rest frame, the asymmetry increases with the t-tbar rapidity difference,
\Delta(y), and with the invariant mass M_t-tbar of the t-tbar system.
Parton-level asymmetries are derived in two regions of each variable, and the
asymmetry is found to be most significant at large \Delta(y) and M_t-tbar.
For M_t-tbar > 450 GeV/c^2, the parton-level asymmetry in the t-tbar rest
frame is A^t-tbar = 0.4750.114 compared to a next-to-leading order QCD
prediction of 0.0880.013.
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