A Revisit to Top Quark Forward-Backward Asymmetry

s 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

A^t_{FB}

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)_d

flavor symemtry is not ruled out by flavor physics. The

t

-channel flavor-violating

Z^{\prime}

\cite{hitoshi},

W^{\prime}

\cite{waiyee} and diquark \cite{tim} models all have parameter regions that satisfy different

A_{FB}

measurements within 1

\sigma

. However, the heavy

Z^{\prime}

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

t \bar{t}

invariant mass distribution. The electroweak precision constraints on the

W'

model based on

Z'

-

Z

mixings is estimated and the result is rather weak (

m_{Z'} > 450

GeV). Therefore, the heavy

W^{\prime}

model seems to give the best fit for all the measurements. The

W^{\prime}

model predicts the

t\bar{t}+j

signal from

tW^{\prime}

production and is 10%-50% of SM

t\bar{t}

at the 7 TeV LHC. Such

t+j

resonance can serve as the direct test of the

W^{\prime}

model.

Note:

25 pages, 7 figures, 1 table

14.65.Ha
angular distribution: asymmetry
jet: pair production
Batavia TEVATRON Coll
diquark: scalar
top: total cross section
rapidity dependence
mass dependence
CERN LHC Coll
CDF

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