Study on fermion mass hierarchy due to vector-like fermions from the bottom up
Study on fermion mass hierarchy due to vector-like fermions from the bottom up
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发表时间：
2019-09
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通讯作者：
Yoshiharu Kawamura
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作者：
Yoshiharu Kawamura
我们研究了费米子质量等级的起源的基础上扩展的标准模型与矢量类费米子，使用自下而上的方法。结果表明，若类矢量费米子与三族混合，则Yukawa耦合矩阵元素的数量级可达到O（1），在扩展模型之外的理论中可实现Yukawa耦合统一.在这种情况下，标准模型中的小Yukawa耦合可以对矩阵元素的微小变化高度敏感，这表明质量层级是微调的结果。
We study an origin of fermion mass hierarchy based on an extension of the standard model with vector-like fermions, using a bottom-up approach. It is shown that a magnitude of elements of Yukawa coupling matrices can become $O(1)$ and a Yukawa coupling unification can be realized in a theory beyond the extended model, if vector-like fermions mix with three families. In this case, small Yukawa couplings in the standard model can be highly sensitive to a small variation of matrix elements, and it suggests that the mass hierarchy occurs as a result of a fine tuning.