A Common Source for Scalars: Axiflavon-Higgs Unification

TL;DR

This paper introduces a unified scalar model combining axiflavon and Higgs sectors, addressing flavor hierarchies, the strong CP problem, dark matter, and electroweak symmetry breaking, with specific bounds on axion decay constants.

Contribution

It unifies axiflavon and Goldstone-Higgs sectors into a single model, linking flavor physics, dark matter, and electroweak symmetry breaking in a novel framework.

Findings

Axion decay constant constrained to (10^{11}-10^{12}) GeV in minimal model.

Adding right-handed neutrinos allows for lower axion decay constants (~10 TeV).

Derived bounds from flavor physics and cosmology on the model parameters.

Abstract

We propose a unified model of scalar particles that addresses the flavour hierarchies, solves the strong CP problem, delivers a dark matter candidate, and provides the trigger for electroweak symmetry breaking. Besides furnishing a unification of the recently proposed axiflavon with a Goldstone-Higgs sector, the scenario can also be seen as adding a model of flavour (and strong CP conservation along with axion dark matter) to elementary Goldstone-Higgs setups. In particular, we derive bounds on the axion decay constant from the need to generate a SM-like Higgs potential at low energies, which we confront with constraints from flavour physics and cosmology. In the minimal implementation, we find that the axion decay constant is restricted to a thin stripe of $f_a \approx (10^{11}-10^{12})$ GeV, while adding right-handed neutrinos allows to realize a heavy-axion model at lower energies, down to $f_a \sim 10$ TeV.