A new type of CP symmetry, family replication and fermion mass hierarchies
A new type of CP symmetry, family replication and fermion mass hierarchies
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新型 CP 对称性、族复制和费米子质量等级
DOI：
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发表时间：
2007
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通讯作者：
O. Nachtmann
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文献类型：
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作者：
M. Maniatis;A. Manteuffel;O. Nachtmann
我们研究了在标量区域具有四个广义CP对称性的双希格斯双态模型。弱电对称破缺会自动导致其中两个的自发破缺。我们要求这四个CP对称性可以从标量扇区扩展到完全拉格朗日，并将这一要求称为最大CP不变性原理。这一要求严重限制了费米子间的汤川相互作用。特别是，单一的费米子家族不可能与希格斯场耦合。然而，对于两个费米子家族来说，这是可能的。在没有改变味道的中性电流的情况下，我们发现两个家庭都有退化的群体，或者一个家庭没有质量，一个家庭有质量。在后一种情况下，拉格朗日是高度对称的，质量等级是由电弱对称破缺产生的。在希格斯场中加入第三个未耦合的族，从而使其保持无质量，我们得到了一个模型，该模型粗略地近似地描述了自然界中观察到的费米子的一些特征。我们讨论了该模型的一些预测，这些预测可能会在未来的大型强子对撞机实验中得到验证。
We study a two-Higgs doublet model with four generalised CP symmetries in the scalar sector. Electroweak symmetry breaking leads automatically to spontaneous breaking of two of them. We require that these four CP symmetries can be extended from the scalar sector to the full Lagrangian and call this requirement the principle of maximal CP invariance. The Yukawa interactions of the fermions are severely restricted by this requirement. In particular, a single fermion family cannot be coupled to the Higgs fields. For two fermion families, however, this is possible. Enforcing the absence of flavour-changing neutral currents, we find degenerate masses in both families or one family massless and one massive. In the latter case the Lagrangian is highly symmetric, with the mass hierarchy being generated by electroweak symmetry breaking. Adding a third family uncoupled to the Higgs fields and thus keeping it massless we get a model which gives a rough approximation of some features of the fermions observed in Nature. We discuss a number of predictions of the model which may be checked in future experiments at the LHC.