The Minimal Flavour Violating Axion

TL;DR

This paper explores a novel axion model within the Minimal Flavour Violation framework, where a new Abelian symmetry addresses the Strong CP problem and exhibits unique couplings affecting astrophysical and collider phenomenology.

Contribution

It introduces the MFV axion, a new solution to the Strong CP problem that differs from traditional axions by its couplings and flavor effects, without inducing flavor violation.

Findings

MFV axion can solve the Strong CP problem.

Distinct couplings from traditional QCD axion.

Phenomenological constraints from astrophysics and colliders.

Abstract

The solution to the Strong CP problem is analysed within the Minimal Flavour Violation (MFV) context. An Abelian factor of the complete flavour symmetry of the fermionic kinetic terms may play the role of the Peccei-Quinn symmetry in traditional axion models. Its spontaneous breaking, due to the addition of a complex scalar field to the Standard Model scalar spectrum, generates the MFV axion, which may redefine away the QCD theta parameter. It differs from the traditional QCD axion for its couplings that are governed by the fermion charges under the axial Abelian symmetry. It is also distinct from the so-called Axiflavon, as the MFV axion does not describe flavour violation, while it does induce flavour non-universality effects. The MFV axion phenomenology is discussed considering astrophysical, collider and flavour data.