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arXiv 2102.07781hep-ph
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求解$Z'$模型中的电子和μ子$g-2$反常

Solving the electron and muon $g-2$ anomalies in $Z'$ models

Arushi Bodas, Rupert Coy, Simon J. D. King

摘要:

我们考虑通过一个$U(1)'$扩展到标准模型(SM)的单个$Z'$的电子和μ子$g-2$异常的同时解释。我们首先进行一个独立于模型的分析可行的风味依赖$Z'$耦合轻子,这是受到各种严格的实验约束。我们发现,只有一个狭窄的区域的参数空间与兆电子伏尺度的$Z'$可以解释这两个异常。根据本分析的结论,然后,我们探讨了不同类别的$Z'$模型实现这些耦合的能力,包括SM $+U(1)'$,$N$ -希格斯双重模型$+U(1)'$,和Froggatt-尼尔森风格的场景。在每种情况下,由于规范结构诱导的带电轻子和中微子与$Z'$耦合之间的额外关系,以及中微子散射边界的严格性,都不能获得必要的耦合组合。因此,我们的结论是,没有$U(1)'$扩展可以解决这两个异常,除非其他新的字段也被引入。虽然我们的大多数研究假设铯$(g-2)_e$测量,但我们的发现实际上也适用于铷测量的情况,尽管两者之间存在紧张关系。

英文摘要:

We consider simultaneous explanations of the electron and muon $g-2$ anomalies through a single $Z'$ of a $U(1)'$ extension to the Standard Model (SM). We first perform a model-independent analysis of the viable flavour-dependent $Z'$ couplings to leptons, which are subject to various strict experimental constraints. We show that only a narrow region of parameter space with an MeV-scale $Z'$ can account for the two anomalies. Following the conclusions of this analysis, we then explore the ability of different classes of $Z'$ models to realise these couplings, including the SM$+U(1)'$, the $N$-Higgs Doublet Model$+U(1)'$, and a Froggatt-Nielsen style scenario. In each case, the necessary combination of couplings cannot be obtained, owing to additional relations between the $Z'$ couplings to charged leptons and neutrinos induced by the gauge structure, and to the stringency of neutrino scattering bounds. Hence, we conclude that no $U(1)'$ extension can resolve both anomalies unless other new fields are also introduced. While most of our study assumes the Caesium $(g-2)_e$ measurement, our findings in fact also hold in the case of the Rubidium measurement, despite the tension between the two.

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