A Model of Visible QCD Axion

TL;DR

This paper explores a class of visible QCD axion models where strong dynamics in a mirrored Standard Model enhance the axion mass, analyzing their consistency with experimental and cosmological constraints.

Contribution

It introduces a novel class of visible axion models with mass enhancement via mirrored strong dynamics and assesses their viability within experimental bounds.

Findings

Viable parameter space with axion mass around 100 MeV or higher.

Peccei-Quinn scale around 10^3 to 10^5 GeV.

Models consistent with laboratory, astrophysical, and cosmological constraints.

Abstract

We pursue a class of visible axion models where the axion mass is enhanced by strong dynamics in a mirrored copy of the Standard Model in the line of the idea put forward by Rubakov. In particular, we examine the consistency of the models with laboratory, astrophysical, and cosmological constraints. As a result, viable parameter regions are found, where the mass of the axion is of $O(100)$ MeV or above while the Peccei-Quinn breaking scale is at around $10^{3\mbox{-}5}$ GeV.