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arXiv · 1909.03623

A bottom-up approach to fermion mass hierarchy: a case with vector-like fermions

Yoshiharu Kawamura
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Abstract

We propose a bottom-up approach that a structure of a high-energy physics is explored by accumulating existence proofs and/or no-go theorems in the standard model or its extension. As an illustration, we study fermion mass hierarchies based on an extension of the standard model with vector-like fermions. 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 seems that the mass hierarchy occurs as a result of a fine tuning.

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Yoshiharu Kawamura. 2019-09-09. A bottom-up approach to fermion mass hierarchy: a case with vector-like fermions. https://doi.org/10.1093/ptep%2Fptaa046

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