GeV ALP from TeV Vector-like leptons

TL;DR

This paper proposes a model predicting a GeV axion-like particle (ALP) linked to TeV-scale vector-like leptons, addressing the muon g-2 anomaly and featuring unique ALP-fermion couplings with broad phenomenological implications.

Contribution

The model introduces a novel connection between GeV ALPs, TeV-scale vector-like leptons, and the muon g-2 anomaly, with unique ALP-fermion coupling features and a low-scale Peccei-Quinn symmetry breaking.

Findings

ALP couplings can vary over many orders of magnitude.

ALP characteristic scale can be as low as the TeV scale.

Model provides a solution to the muon g-2 anomaly.

Abstract

We present a model where a GeV axion-like-particle (ALP) is predicted in a large portion of the parameter space due to the presence of explicit Peccei-Quinn symmetry-breaking terms in an exotic leptonic sector. The latter provides a solution to the muon $g-2$ anomaly, within the framework of the Linear Seesaw neutrino mechanism. The spectrum is extended by a complex scalar singlet only transforming under the Peccei-Quinn symmetry, which generates the ALP. Its couplings with fermions can continuously span over many orders of magnitude, which constitutes a specific feature of this model in contrast to generic ultraviolet constructions. Interestingly, these couplings are suppressed by the ALP characteristic scale that can be as low as the TeV scale, which represents a novel feature of the model and opens up to several phenomenological consequences.