Top quark forward-backward asymmetry, flavor-changing neutral-current decays, and like-sign pair production as a joint probe of new physics

The anomaly of the top quark forward-backward asymmetry AFBt observed at the Tevatron can be explained by the t-channel exchange of a neutral gauge boson (Z') which has sizable flavor-changing coupling for top and up quarks. This gauge boson can also induce the top quark flavor-changing neutral-current (FCNC) decays and the like-sign top pair production at the LHC. In this work, we focus on two models which predict such a Z', namely, the left-right model and the U(1)X model, to investigate the correlated effects on AFBt, the FCNC decays t→uV (V=g, Z, γ) and the like-sign top pair production at the LHC. We also pay special attention to the most recently measured AFBt in the large top pair invariant mass region. We find that under the current experimental constraints both models can alleviate the deviation of AFBt and, meanwhile, enhance the like-sign top pair production to the detectable level of the LHC. We also find that the two models give different predictions for the observables and their correlations, and thus they may even be distinguished by jointly studying these top quark observables.