Has the Origin of the Third-Family Fermion Masses been Determined?

TL;DR

This paper investigates whether current and future Higgs coupling measurements can differentiate between the Standard Model's tree-level fermion mass generation and alternative radiative mechanisms, focusing on third-family fermions.

Contribution

It classifies minimal one-loop models for radiative third-family fermion mass generation and assesses their compatibility with current and future collider data.

Findings

Radiative models for tau and bottom masses are consistent with current data.

Future colliders can explore parameter regions but may not definitively rule out radiative origins.

Two main classes of one-loop models are identified and analyzed.

Abstract

Precision measurements of the Higgs couplings are, for the first time, directly probing the mechanism of fermion mass generation. The purpose of this work is to determine to what extent these measurements can distinguish between the tree-level mechanism of the Standard Model and the theoretically motivated alternative of radiative mass generation. Focusing on the third-family, we classify the minimal one-loop models and find that they fall into two general classes. By exploring several benchmark models in detail, we demonstrate that a radiative origin for the tau-lepton and bottom-quark masses is consistent with current observations. While future colliders will not be able to rule out a radiative origin, they can probe interesting regions of parameter space.