An even lighter QCD axion

A bstract We explore whether the axion which solves the strong CP problem can naturally be much lighter than the canonical QCD axion. The Z N symmetry proposed by Hook, with N mirror and degenerate worlds coexisting in Nature and linked by the axion field, is considered in terms of generic effective...

Full description

Saved in:
Bibliographic Details
Published in:The journal of high energy physics 2021-05, Vol.2021 (5), p.1-36, Article 184
Main Authors: Di Luzio, Luca, Gavela, Belen, Quilez, Pablo, Ringwald, Andreas
Format: Article
Language:English
Subjects:
Beyond Standard Model
Chiral Lagrangians
Classical and Quantum Gravitation
Constraint modelling
Couplings
CP violation
Density
Discrete Symmetries
Elementary Particles
Gravitational waves
High energy physics
Neutron stars
Physics
Physics and Astronomy
Quantum chromodynamics
Quantum Field Theories
Quantum Field Theory
Quantum Physics
Regular Article - Theoretical Physics
Relativity Theory
String Theory
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:A bstract We explore whether the axion which solves the strong CP problem can naturally be much lighter than the canonical QCD axion. The Z N symmetry proposed by Hook, with 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 N limit, and we determine the analytical formula for the exponentially suppressed axion mass. The resulting universal enhancement of all axion interactions relative to those of the canonical QCD axion has a strong impact on the prospects of axion-like particle experiments such as ALPS II, IAXO and many others: experiments searching for generic axion-like particles have in fact discovery potential to solve the strong CP problem. The finite density axion potential is also analyzed and we show that the Z N asymmetric background of high-density stellar environments sets already significant model-independent constraints: 3 ≤ N ≲ 47 for an axion scale f a ≲ 2 . 4 × 10 15 GeV, with tantalizing discovery prospects for any value of f a and down to N ∼ 9 with future neutron star and gravitational wave data, down to the ultra-light mass region. In addition, two specific ultraviolet Z N completions are developed: a composite axion one and a KSVZ-like model with improved Peccei-Quinn quality.
ISSN:1029-8479
1029-8479
DOI:10.1007/JHEP05(2021)184