Flavor Hierarchy from Smooth Confinement

TL;DR

This paper proposes a supersymmetric model where smooth confinement at an intermediate scale explains the Standard Model flavor hierarchy, with composite first and second family fermions and a natural parameter setup.

Contribution

It introduces a novel supersymmetric confinement mechanism that generates flavor hierarchy and fermion compositeness, differing from previous models by specific matter content and superpotential deformations.

Findings

First and second family fermions are composite, third family is elementary.

Flavor hierarchy arises from exponential suppression due to dimensional transmutation.

Model maintains gauge symmetries until Higgs condensation breaks them.

Abstract

We present a model to explain the Standard Model flavor hierarchy. Our model is based on explicit smooth confinement (namely confinement without chiral symmetry breaking in a supersymmetric gauge theory) at an intermediate energy scale, before the electroweak symmetry breaking by the Higgs condensation at lower energy. In our context, the smooth confinement preserves the SU(3) and the chiral SU(2)$_L\times$ U(1)$_Y$ symmetry in a supersymmetric Standard Model, while this internal symmetry becomes dynamically gauged in the end. In contrast to Razamat-Tong's symmetric mass generation model also preserving the $G_{\rm SM} \equiv$ SU(3)$_C\times$ SU(2)$_L\times$ U(1)$_Y$ internal symmetry, our model introduces different matter contents with a different kind of superpotential deformation irrelevant at UV, which further induces Yukawa-Higgs terms marginal at IR, breaking the $G_{\rm SM}$ down to SU(3)$_C$ and the electromagnetic U(1)$_{\rm EM}$ only when Higgs condenses. In our model, the IR fermions in the first and second families are composite of UV fields, while the third family elementary fermions match between UV and IR. The smallness of the first and second family fermion masses is explained by the exponential hierarchy between the cutoff scale and the smooth confinement scale via dimensional transmutation. As a result, our UV Lagrangian only contains the natural parameters close to the order one.