Diluting quark flavor hierarchies using dihedral symmetry

TL;DR

This paper introduces a $D_4$ flavor symmetry extension of the Standard Model that explains quark mass hierarchies and mixing angles, linking the CKM matrix structure to scalar sector dynamics and quark mass scales.

Contribution

It proposes a novel $D_4$ flavor symmetry model that naturally accounts for quark mass hierarchies and mixing patterns, especially the Cabibbo angle, through scalar sector dynamics.

Findings

Cabibbo angle arises from scalar sector dynamics

CKM element magnitudes linked to vacuum expectation value hierarchies

Small off-Cabibbo CKM elements connected to heavy third-generation quarks

Abstract

We present a $D_4$ flavored extension of the SM which provides an intuitive reasoning for the masses and mixing patterns in the quark sector. In our model, the Cabibbo mixing angle stems purely from the scalar sector dynamics. In fact, the orders of magnitude of the CKM matrix elements are readily obtained from the hierarchical nature of the vacuum expectation values. Moreover, we also show that the smallness of the off-Cabibbo elements in the CKM matrix is strongly connected to the heaviness of the third generation of quarks.