arXiv 1602.074372016-02hep-ph

$A_4$味对称标准模型的跷跷板方案

A see-saw scenario of an $A_4$ flavour symmetric standard model

Dinh Nguyen Dinh, Nguyen Anh Ky, Phi Quang Văn, Nguyen Thi Hông Vân

备注：: LaTeX, 31 pages, 12 figures, 6 tables. V3: some parts modified

摘要：

提出了一种$A_4$味对称标准模型的跷跷板方案。与标准模型相比，后者具有扩展的场内容，现在采用额外的$A_4$对称结构（连同标准模型对称性）。和以前一样，跷跷板机制可以在几种不同类型的模型中实现，这取决于中微子质量产生的不同方式，对应于引入具有不同对称结构的新场（一般是重场）。在本文中，所有这些跷跷板类型的一般性描述与I型模型进行了更详细的调查，而对于II型和III型模型可以遵循类似的策略。在原来的跷跷板机制中，标准模型场的对称结构决定了新场的数量和对称结构。在这里考虑的一个模型中，标量扇区由三个标准模型的希格斯类等二重态（$SU_L(2)$ -二重态）和三个等单重态组成，这三个等二重态共同形成一个$A_4$ -三重态，三个等单重态转变为$A_4$的三个单重态（1，$1^{'}$和$1^{''}$）。在轻子扇区中，三个左手轻子的等二重态形成一个$A_4$ -三重态，而三个右手带电轻子在一个模型中是$A_4$ -单线态，在另一个模型中是$A_4$ -三重态的组成部分。为了通过I型跷跷板机制产生中微子质量，很自然地要添加四个右手中微子多重态，包括一个$A_4$ -三重态和三个$A_4$ -单线态。作为解释，利用该模型导出了无中微子双β衰变有效质量$|\langle m_{ee}\rangle|$、CP破坏相$δ_{CP}$和Jarlskog参数$J_{CP}$等物理量，并得到了实验验证。

英文摘要：

A see-saw scenario for an $A_4$ flavour symmetric standard model is presented. The latter, compared with the standard model, has an extended field content adopting now an additional $A_4$ symmetry structure (along with the standard model symmetry). As before, the see-saw mechanism can be realized in several models of different types depending on different ways of neutrino mass generation corresponding to the introduction of new (heavy in general) fields with different symmetry structures. In the present paper, a general description of all these see-saw types is made with a more detailed investigation on type-I models, while for type-II and type-III models a similar strategy can be followed. As within the original see-saw mechanism, the symmetry structure of the standard model fields decides the number and the symmetry structure of the new fields. In a model considered here, the scalar sector consists of three standard-model-Higgs-like iso-doublets ($SU_L(2)$-doublets) forming together an $A_4$-triplet, and three iso-singlets transforming as three singlets (1,$1^{'}$ and $1^{''}$) of $A_4$. In the lepton sector, the three left-handed lepton iso-doublets form an $A_4$-triplet, while the three right-handed charged leptons are either $A_4$-singlets in one version of the model, or components of an $A_4$-triplet in another version. To generate neutrino masses through, say, the type-I see-saw mechanism, it is natural to add four right-handed neutrino multiplets, including one $A_4$-triplet and three $A_4$-singlets. For an interpretation, the model is applied to deriving some physics quantities such as neutrinoless double beta decay effective mass $|\langle m_{ee}\rangle|$, CP violation phase $δ_{CP}$ and Jarlskog parameter $J_{CP}$, which can be verified experimentally.

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摘要：

英文摘要：

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