# An even lighter QCD axion

@article{DiLuzio2021AnEL, title={An even lighter QCD axion}, author={Luca Di Luzio and Belen Gavela and Pablo Quilez and Andreas Ringwald}, journal={Journal of High Energy Physics}, year={2021}, volume={2021}, pages={184} }

We explore whether the axion which solves the strong CP problem can naturally be much lighter than the canonical QCD axion. The $Z_\mathcal{N}$ symmetry proposed by Hook, with $\mathcal{N}$ mirror and degenerate worlds coexisting in Nature and linked by the axion field, is considered in terms of generic effective axion couplings. We show that the total potential is safely approximated by a single cosine in the large $\mathcal{N}$ limit, and we determine the analytical formula for the…

## 24 Citations

Photophilic hadronic axion from heavy magnetic monopoles

- PhysicsJournal of High Energy Physics
- 2021

Abstract
We propose a model for the QCD axion which is realized through a coupling of the Peccei-Quinn scalar field to magnetically charged fermions at high energies. We show that the axion of this…

Axion Couplings in Grand Unified Theories

- Physics
- 2022

: We show that the couplings of axions to gauge bosons are highly restricted in Grand Uniﬁed Theories where the standard model is embedded in a simple 4D gauge group. The topological nature of these…

Dark matter from an even lighter QCD axion: trapped misalignment

- PhysicsJournal of Cosmology and Astroparticle Physics
- 2021

We show that dark matter can be accounted for by an axion that solves the strong CP problem, but is much lighter than usual due to a Z 𝒩 symmetry. The whole mass range from the canonical QCD axion…

Axion dark matter from frictional misalignment

- Physics
- 2022

We study the impact of sphaleron-induced thermal friction on the axion dark-matter abundance due to the interaction of an axion-like particle (ALP) with a dark non-abelian gauge sector in a secluded…

Novel cosmological bounds on thermally-produced axion-like particles

- Physics
- 2022

. We constrain the coupling of thermally-produced axion-like particles (here axions) with photons and gluons, using data from the cosmic microwave background (CMB) spectra and baryon acoustic…

One-loop corrections to ALP couplings

- PhysicsJournal of High Energy Physics
- 2021

Abstract
The plethora of increasingly precise experiments which hunt for axion-like particles (ALPs), as well as their widely different energy reach, call for the theoretical understanding of ALP…

S.M.A.S.H.E.D.: Standard Model Axion Seesaw Higgs Inflation Extended for Dirac Neutrinos

- Physics
- 2022

Inspired by the S.M.A.S.H. framework we construct a model that addresses the strong CP problem, axion dark matter, inflation and Dirac neutrino masses as well as leptogenesis. The model possesses…

One-loop corrections to ALPs couplings

- Physics
- 2021

The plethora of increasingly precise experiments which hunt for axion-like particles (ALPs), as well as their widely different energy reach, call for the theoretical understanding of ALP couplings at…

Oscillations of atomic energy levels induced by QCD axion dark matter

- Physics
- 2022

Axion-gluon interaction induces quadratic couplings between the axion and the matter ﬁelds. We ﬁnd that, if the axion is an ultralight dark matter ﬁeld, it induces small oscillations of the mass of…

Axion signatures from supernova explosions through the nucleon electric-dipole portal

- PhysicsPhysical Review D
- 2022

We consider axions coupled to nucleons and photons only through the nucleon electric-dipole moment (EDM) portal. This coupling is a model-independent feature of QCD axions, which solve the strong CP…

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