A mechanism relating the fermionic mass hierarchy to the flavor mixing

TL;DR

This paper proposes a new mechanism linking fermionic mass hierarchy and flavor mixing using the see-saw mechanism, explaining both puzzles simultaneously and suggesting experimental tests through rare decay processes.

Contribution

It introduces a novel fermion sector mechanism connecting mass hierarchy and flavor mixing, supported by a flavor-dependent model and testable via rare decay observations.

Findings

The mechanism explains fermion mass hierarchy and flavor mixing puzzles.

The flavor-dependent model realizes the proposed mechanism.

Predicted rare decay processes can test the model.

Abstract

Considering the hierarchical structure of fermionic masses and the fermionic flavor mixing puzzles in the Standard Model, we propose to relate them by the see-saw mechanism, i.e. only the third generation of quarks and charged leptons achieve the masses at the tree level, the first two generations achieves masses through the mixings with the third generation, and the neutrinos achieve tiny Majorana masses by the so-called Type-I see-saw mechanism. This new picture at the fermion sector can explain simultaneously the flavor mixing puzzle and mass hierarchy puzzle in the SM. In addition, a flavor-dependent model (FDM) is proposed to realize the new mechanism, and observing the top quark rare decay processes $t\to ch$, $t\to uh$ and the lepton flavor violation processes $\mu\to3e,\;\tau\to3e,\;\mu\to3\mu$ is effective to test the proposed FDM.