arXiv 1601.009772016-01hep-ph

扩展$A_4$味的一个新的平凡CP对称性

A new and trivial CP symmetry for extended $A_4$ flavor

C. C. Nishi

备注：: 23pp, 7 figs; v2: published version with small updates in text
发表信息：: Phys. Rev. D 93, 093009 (2016)
DOI：: 10.1103/PhysRevD.93.093009

摘要：

$ν_μ$交换与中微子扇区中的CP共轭（称为$\mathrm{CP}^{μτ}$对称性或$μτ$ -反射）的组合已知可以预测可行的模式：$θ_{23}=45^\circ$，最大狄拉克CP相位和平凡马约拉纳相位。我们实现这样的CP对称性作为一个新的CP对称性的理论与$A_4$风味。在一个完整的可重整化模型的实施导致一个新的形式的中微子质量矩阵，导致进一步的预测：正常的分级光谱与最轻的质量和$m_{ββ}$（$0νββ$）只有几个meV，无论是$ν_1$或$ν_2$有相反的CP宇称。近似的$L_μ-L_τ$对称性自然产生并控制模型的风味结构。轻中微子质量由6个右手中微子的扩展跷跷板机制产生。对轻中微子质量的单圈修正可以忽略不计，扩展的跷跷板近似的有效性和不太长寿命的BSM态符合BBN的要求基本上限制了模型的参数到一个小区域：三个相对较轻的右手中微子在GeV尺度，较重的中微子在电弱尺度和Yukawa耦合小于电子Yukawa。如此小的汤川耦合使得这些RHN在地面实验中不可观测。

英文摘要：

The combination of $ν_μ$-$ν_τ$ exchange together with CP conjugation in the neutrino sector (known as $\mathrm{CP}^{μτ}$ symmetry or $μτ$-reflection) is known to predict the viable pattern: $θ_{23}=45^\circ$, maximal Dirac CP phase and trivial Majorana phases. We implement such a CP symmetry as a new CP symmetry in theories with $A_4$ flavor. The implementation in a complete renormalizable model leads to a new form for the neutrino mass matrix that leads to further predictions: normal hierarchical spectrum with lightest mass and $m_{ββ}$ ($0νββ$) of only few meV, and either $ν_1$ or $ν_2$ has opposite CP parity. An approximate $L_μ-L_τ$ symmetry arises naturally and controls the flavor structure of the model. The light neutrino masses are generated by the extended seesaw mechanism with 6 right-handed neutrinos (RHNs). The requirement of negligible one-loop corrections to light neutrino masses, validity of the extended seesaw approximation and not too long-lived BSM states to comply with BBN essentially restricts the parameters of the model to a small region: three relatively light right-handed neutrinos at the GeV scale, heavier neutrinos at the electroweak scale and Yukawa couplings smaller than the electron Yukawa. Such a small Yukawa couplings render these RHNs unobservable in terrestrial experiments.

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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英文摘要：

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