From axion quality and naturalness problems to a high-quality ${\mathbb{Z}}_N$ QCD relaxion

Abstract

We highlight general issues associated with quality and naturalness problems in theories of light QCD-axions, axion-like particles, and relaxions. We show the presence of Planck-suppressed operators generically lead to scalar coupling of axions with the Standard model. We present a new class of ${\mathbb{Z}}_N$ QCD relaxion models that can address both the QCD relaxion CP problem as well as its quality problem. This new class of models also leads to interesting experimental signatures, which can be searched for at the precision frontier.

17 pages, 4 figures; v2: previously ignored effects related to higher harmonics included, available parameter space updated, discussion extended; v3: matches the PRD accepted version

References in corpus (27)

• Test of the Equivalence Principle Using a Rotating Torsion Balance
• Measurement of the permanent electric dipole moment of the neutron
• Searching for dilaton dark matter with atomic clocks
• Equivalence Principle Violations and Couplings of a Light Dilaton
• Search for ultralight scalar dark matter with atomic spectroscopy
• Resonant detection of axion mediated forces with Nuclear Magnetic Resonance
• Short-range tests of the equivalence principle
• Searching for dark matter and variation of fundamental constants with laser and maser interferometry
• Precision Metrology Meets Cosmology: Improved Constraints on Ultralight Dark Matter from Atom-Cavity Frequency Comparisons
• Natural inflation with multiple sub-Planckian axions
• A Clockwork Theory
• Anomalous solutions to the strong CP problem
• An even lighter QCD axion
• Relaxation from particle production
• Direct limits for scalar field dark matter from a gravitational-wave detector
• Dark matter from an even lighter QCD axion: trapped misalignment
• Searching for Scalar Dark Matter via Coupling to Fundamental Constants with Photonic, Atomic and Mechanical Oscillators
• Search for oscillations of fundamental constants using molecular spectroscopy
• Constraints on scalar field dark matter from co-located Michelson interferometers
• Neutron electric dipole moment using lattice QCD simulations at the physical point
• Result of the MICROSCOPE Weak Equivalence Principle test
• QCD $\theta$-vacuum energy and axion properties
• Relaxion: A Landscape Without Anthropics
• Search of spin-dependent fifth forces with precision magnetometry
• A Custodial Symmetry for Muon g-2
• Axion model with the $\mathrm{SU}(6)$ unification
• The Axion Quality and Fifth Force

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• Nelson-Barr ultralight dark matter
• Nuclear decay anomalies as a signature of axion dark matter
• Imperfect Axion Precludes the Domain Wall Problem
• A Lighter QCD Axion from Anarchy
• Weak nuclear decays deep-underground as a probe of axion dark matter
• Stacking the Deck: Gambling on a Light QCD Axion