期刊
PHYSICAL REVIEW D
卷 81, 期 1, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevD.81.014016
关键词
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资金
- National Natural Science Foundation of China (NNSFC) [10505007, 10821504, 10725526, 10635030]
- HASTIT [2009HASTIT004, 2010IRTSTHN002]
- Chinese Academy of Sciences [KJCX2.YW.W10]
The top quark forward-backward asymmetry A(FB)(t) measured at the Tevatron is above the standard model prediction by more than 2 sigma deviation, which might be a harbinger for new physics. In this work we examine the contribution to A(FB)(t) in two different new physics models: one is the minimal supersymmetric model without R parity which contributes to A(FB)(t) via sparticle-mediated t channel process d (d) over bar -> t (t) over bar; the other is the third-generation enhanced left-right model which contributes to A(FB)(t) via Z'-mediated t channel or s channel processes. We find that in the parameter space allowed by the t (t) over bar production rate and the t (t) over bar invariant mass distribution at the Tevatron, the left-right model can enhance A(FB)(t) to within the 2 sigma region of the Tevatron data for the major part of the parameter space, and in optimal case A(FB)(t) can reach 12% which is slightly below the 1 sigma lower bound. For the minimal supersymmetric model without R parity, only in a narrow part of the parameter space can the lambda '' couplings enhance A(FB)(t) to within the 2 sigma region while the lambda' couplings just produce negative contributions to worsen the fit.
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