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arXiv 0808.2113hep-ph
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超对称理论中$Λ_b \to Λl^{+} l^{-}$的排斥半轻子衰变

Exclusive semileptonic decays of $Λ_b \to Λl^{+} l^{-}$ in supersymmetric theories

M. Jamil Aslam, Yu-Ming Wang, Cai-Dian Lu

摘要:

在最小超对称标准模型(MSSM)和超对称(SUSY)SO(10)大统一模型中研究了$Λ_b \to Λl^{+} l^{-}$($l=e, μ$)的弱衰变.在MSSM中,中性希格斯玻色子(NHB)对超对称模型参数空间中大$\tanβ$区域的排他性$B \to X_{s} l^{+} l^{-}$衰变有很大贡献,因为部分超对称贡献与$\tan^{3}β$成正比.对衰变率、前向-后向不对称性、轻子极化不对称性和$Λ_b \to Λl^{+} l^{-}$中$Λ$重子的极化不对称性的分析表明,NHB对这些物理观测量的影响很大.在SUSY SO(10)GUT模型中,新的物理贡献来自于NHB企鹅诱导的算符,也来自于手征性与相应SM算符相反的算符。SUSY SO(10)效应只在$Λ_b \to Λ+τ^{+} τ^{-}$衰变中出现,此时轻子的纵向和横向极化不对称性都显著偏离SM值,而对末态$Λ$重子的衰变率、前后向不对称性和极化不对称性的影响很小. $Λ_b \to Λ+τ^{+} τ^{-}$中的横轻子极化不对称性在SM和MSSM模型中几乎为零。然而,在SUSY SO(10)GUT模型中,它可以达到-0.1,并且可以在未来的对撞机上看到;因此,这种可观察到的不对称性将为我们探索新物理和区分不同模型提供有用的信息。

英文摘要:

The weak decays of $Λ_b \to Λl^{+} l^{-}$ ($l=e, μ$) are investigated in Minimal Supersymmetric Standard Model (MSSM) and also in Supersymmetric (SUSY) SO(10) Grand Unified Models. In MSSM the special attention is paid to the Neutral Higgs Bosons (NHBs) as they make quite a large contribution in exclusive $B \to X_{s} l^{+} l^{-}$ decays at large $\tanβ$ regions of parameter space of SUSY models, since part of SUSY contributions is proportional to $\tan^{3}β$. The analysis of decay rate, forward-backward asymmetries, lepton polarization asymmetries and the polarization asymmetries of $Λ$ baryon in $Λ_b \to Λl^{+} l^{-}$ show that the values of these physical observables are greatly modified by the effects of NHBs. In SUSY SO(10) GUT model, the new physics contribution comes from the operators which are induced by the NHBs penguins and also from the operators having chirality opposite to that of the corresponding SM operators. SUSY SO(10) effects show up only in the decay $Λ_b \to Λ+τ^{+} τ^{-}$ where the longitudinal and transverse lepton polarization asymmetries are deviate significantly from the SM value while the effects in the decay rate, forward-backward asymmetries and polarization asymmetries of final state $Λ$ baryon are very mild. The transverse lepton polarization asymmetry in $Λ_b \to Λ+τ^{+} τ^{-}$ is almost zero in SM and in MSSM model. However, it can reach to -0.1 in SUSY SO(10) GUT model and could be seen at the future colliders; hence this asymmetry observable will provide us useful information to probe new physics and discriminate between different models.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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