科研之友
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摘要
A flavor symmetry based on Z(4) is analyzed in the context of SU(5) Grand Unification with the standard fermionic content plus three right-handed neutrinos. The role of Z(4) is to forbid some Yukawa couplings of up-and down-quarks to Higgs scalars such that the quark mass matrices M-u, M-d have Nearest-Neighbor-Interaction (NNI) structure, once they are generated through the electroweak symmetry breaking. It turns out in this framework that Z(4) is indeed the minimal discrete symmetry and its implementation requires the introduction of at least two Higgs quintets, which leads to a two Higgs doublet model at low energy scale. Because of the SU(5) unification, it is shown that the charged lepton mass matrix develops also NNI form. However, the effective neutrino mass matrix exhibits a nonparallel pattern, in the framework of the type-I seesaw mechanism. Analyzing all possible zero textures allowed by gauge-horizontal symmetry SU(5) X Z(4), it is seen that only two patterns are in agreement with the leptonic experimental data and they could be further distinguished by the light neutrino mass spectrum hierarchy. It is also demonstrated that Z(4) freezes out the possibility of proton decay through exchange of color Higgs triplets at tree-level.
- 出版日期2012-1-6
