Imperfect Axion Precludes the Domain Wall Problem

Abstract

The QCD axion needs not be an exact pseudoscalar for solving the strong CP problem. Its imperfectness can play a profound role cosmologically. We propose effective operators, where the Peccei-Quinn field linearly couples to Standard Model particles, provide a dynamical solution to the domain wall problem that prevails in post-inflationary axion models with discrete symmetry. Such interactions generate a thermal potential that drives the axion field to a universal value throughout the universe at high temperatures thus preventing the birth of domain walls when the QCD potential switches on. We discuss generic conditions for this mechanism to work and several concrete examples. Combining with existing electric dipole moment and fifth force constraints, a lower bound on the axion mass is obtained around $10^{-5}$\,eV. Our findings make a strong case for complementary axion searches with both quality preserving and violating interactions.

arXiv comment6 pages, 2 figures

References in corpus (36)

• Axion Cosmology
• New experimental approaches in the search for axion-like particles
• The landscape of QCD axion models
• A Search for Invisible Axion Dark Matter with the Axion Dark Matter Experiment
• Measurement of the permanent electric dipole moment of the neutron
• Update on scalar singlet dark matter
• Planck-Scale Physics and the Peccei-Quinn Mechanism
• Solutions to the strong CP problem in a world with gravity
• Extended Search for the Invisible Axion with the Axion Dark Matter Experiment
• Invisible Axion Search Methods
• First results from a microwave cavity axion search at 24 micro-eV
• Axion dark matter from topological defects
• Results from phase 1 of the HAYSTAC microwave cavity axion experiment
• Stellar cooling bounds on new light particles: plasma mixing effects
• Physics potential of the International Axion Observatory (IAXO)
• Axion Dark Matter Search around 6.7 $\mu$eV
• Galactic axions search with a superconducting resonant cavity
• Studies of the motion and decay of axion walls bounded by strings
• Limits on a CP-violating scalar axion-nucleon interaction
• A new experimental approach to probe QCD axion dark matter in the mass range above 40$\mu$eV
• Axion dark matter in the post-inflationary Peccei-Quinn symmetry breaking scenario
• IS THERE A DOMAIN WALL PROBLEM?
• A New Cryogenic Apparatus to Search for the Neutron Electric Dipole Moment
• New confining force solution of QCD axion domain wall problem
• First ultracold neutrons produced at TRIUMF
• The meso-inflationary QCD axion
• Cosmic implications of a low-scale solution to the axion domain wall problem
• Ruling out light axions: the writing is on the wall
• Distinguishing axions from generic light scalars using EDM and fifth-force experiments
• The QUAX-g_p g_s experiment to search for monopole-dipole Axion interaction
• Axion-mediated forces, CP violation and left-right interactions
• CP-violating axion interactions in effective field theory
• Long-range axion forces and hadronic CP violation
• From axion quality and naturalness problems to a high-quality ${\mathbb{Z}}_N$ QCD relaxion
• The Flavor of QCD Axion Dark Matter
• The Axion Quality and Fifth Force

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