Common source for scalars: Flavored axion-Higgs unification

Abstract

We propose a unified model of scalar particles that addresses the flavor 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 flavor (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 Standard-Model-like Higgs potential at low energies, which we confront with constraints from flavor physics. In the minimal implementation, we find that the axion decay constant is restricted to a thin stripe of ${f}_{a}\ensuremath{\approx}({10}^{11}--1{0}^{12})\text{ }\text{ }\mathrm{GeV}$, while adding right-handed neutrinos allows to realize a heavy-axion model at lower energies, down to ${f}_{a}\ensuremath{\sim}10\text{ }\text{ }\mathrm{TeV}$.