Implications of the CDF tt̄ forward-backward asymmetry for hard top physics

The CDF collaboration has recently reported a large deviation from the stan- dard model of the tt̄ forward-backward asymmetry in the high invariant mass region. We interpret this measurement as coming from new physics at a heavy scale δ, and perform a model-independent analysis up to O(1=δ⁴) . A simple formalism to test and constrain models of new physics is provided. We find that a large asymmetry cannot be accommo- dated by heavy new physics that does not interfere with the standard model. We show that a smoking gun test for the heavy new physics hypothesis is a significant deviation from the standard model prediction for the tt̄ differential cross section at large invariant mass. At Mtt̄ >1TeV the cross section is predicted to be at least twice that of the SM at the Tevatron, and for Mtt̄ >1:5TeV at least three times larger than the SM at the LHC.