A Factorized Mass Structure of Fermions and Its Fit

Abstract

The structure of the mass matrix, a challenging problem in the Standard Model, is closely related to flavor phenomenology and the understanding of the Yukawa interaction. We derive a factorized mass structure based on observed fermion mass hierarchies, investigating the role of $SO(2)^f$ family symmetry in explaining the approximate degeneracy of light quark generations and its connection to flavor mixing. Our calculation includes the slightest modification from the lightest fermions by $\mathcal{O}(h^2)$ hierarchy corrections. Using this model-independent framework, we systematically analyze all mass patterns and perform comprehensive fits to both quark CKM and lepton PMNS mixing data with extended normal-ordered Dirac neutrinos. The results demonstrate this framework's capacity to unify flavor phenomena while simultaneously providing new insights into the fundamental nature of Yukawa interactions.