Abstract: We present a new measurement of the inclusive forward-backward tt
production asymmetry and its rapidity and mass dependence. The measurements are performed with data corresponding to an integrated luminosity of 5:3 fb
1 of pp
collisions at ffiffis p ¼ 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 tt
rapidity difference, y, and with the invariant mass Mtt
of the tt
system. Fully corrected parton-level asymmetries are derived in two regions of each variable, and the asymmetry is found to be most significant at large y and Mtt
. For Mtt
450 GeV=c2, the parton-level asymmetry in the tt
rest frame is Att
¼ 0:475 0:114 compared to a next-to-leading order QCD prediction of 0:088 0:013.

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