Generating the fermion mass hierarchy at the TeV scale

TL;DR

This paper introduces models with TeV-scale new physics that naturally generate fermion mass hierarchies and mixing angles while suppressing flavor and CP violations, making them testable at current and future colliders.

Contribution

The paper presents a novel class of theories using chain-like structures to produce hierarchical Yukawa matrices at TeV scale without large flavor violations.

Findings

Hierarchical Yukawa matrices are generated via chain locality.

Models predict small flavor and CP violations despite TeV-scale new particles.

Potential collider signatures include production and decay of vector-like fermions.

Abstract

We propose a class of theories to generate quark and lepton mass matrices where the scale of new physics is at the TeV scale, without inducing the large flavor and CP violating processes that are often thought to relegate the origin of flavor to energies above $\sim 100$ TeV. The models have new vector-like leptons and quarks, with mass mixings to each other and Yukawa couplings to light Standard Model fields encoded in "chains" reminiscent of dimensional deconstruction. Locality in the chains both generates the hierarchical Standard Model Yukawa matrices, and ensures that CP and flavor violating effects are small, even with the vector-like particles at the TeV scale. A simple extension also generates neutrino masses, whose tiny size is parametrically related to the square of the electron Yukawa coupling. We outline the essential features of these models, explain how fermion mass hierarchies and mixing angles emerge, and explore their phenomenological implications. This framework can be tested both in the final run of the LHC as well as at possible future colliders operating at the 10 TeV scale, and we identify some of the distinctive experimental signatures associated with the production and decay of the new vector-like fermions.