We analyze various models for the top quark forward-backward asymmetry
(AFBtβ) at the Tevatron, using the latest CDF measurements on different
AFBtβs and the total cross section. The axigluon model in Ref. \cite{paul}
has difficulties in explaining the large rapidity dependent asymmetry and mass
dependent asymmetry simultaneously and the parameter space relevant to
AFBtβ is ruled out by the latest dijet search at ATLAS. In contrast to
Ref. \cite{cp}, we demonstrate that the large parameter space in this model
with a U(1)dβ flavor symemtry is not ruled out by flavor physics. The
t-channel flavor-violating Zβ² \cite{hitoshi},
Wβ²\cite{waiyee} and diquark \cite{tim} models all have parameter
regions that satisfy different AFBβ measurements within 1 Ο.
However, the heavy Zβ² model which can be marginally consistent with
the total cross section is severely constrained by the Tevatron direct search
of same-sign top quark pair. The diquark model suffers from too large total
cross section and is difficult to fit the ttΛ invariant mass
distribution. The electroweak precision constraints on the Wβ² model based on
Zβ²-Z mixings is estimated and the result is rather weak (mZβ²β>450
GeV). Therefore, the heavy Wβ² model seems to give the best fit for
all the measurements. The Wβ² model predicts the ttΛ+j signal
from tWβ² production and is 10%-50% of SM ttΛ at the 7 TeV LHC.
Such t+j resonance can serve as the direct test of the Wβ² model.Comment: 25 pages, 7 figures, 1 tabl