Inequalities for Standard Model Yukawa Couplings

TL;DR

This paper derives basis-independent inequalities for Standard Model Yukawa matrices, providing strong constraints on fermion mass hierarchies and flavor model building.

Contribution

It introduces novel basis-invariant inequalities for Yukawa matrices, offering new constraints on fermion mass and mixing structures in the Standard Model.

Findings

Yukawa matrices satisfy basis-independent inequalities

Constraints on alignment of Yukawa matrix columns

Implications for flavor model building

Abstract

We show that the Standard Model Yukawa matrices satisfy a set of simple yet nontrivial inequalities. The relations we derive are independent of the basis used to define the fermion fields, and, amongst other things, place strong constraints on the alignment of the columns of the up-type and down-type Yukawa matrices, as well as their cofactor matrices. The reason why one can obtain such strong statements can be traced back to the hierarchical nature of the fermion masses and quark mixings. The inequalities should be seen as very strong necessary conditions on the Standard Model Yukawa couplings and thus are useful for constraining flavor models.