Dark matter from an even lighter QCD axion: trapped misalignment

Abstract

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 $Z_{\mathcal{N}}$ symmetry. The whole mass range from the canonical QCD axion down to the ultra-light regime is allowed, with $3\le \mathcal{N}\lesssim 65$. This includes the first proposal of a "fuzzy dark matter" QCD axion with $m_a\sim 10^{-22}$ eV. A novel misalignment mechanism occurs --{\it trapped misalignment}-- due to the peculiar temperature dependence of the $Z_{\mathcal{N}}$ axion potential. The dark matter relic density is enhanced because the axion field undergoes two stages of oscillations: it is first trapped in the wrong minimum, which effectively delays the onset of true oscillations. Trapped misalignment is more general than the setup discussed here, and may hold whenever an extra source of Peccei-Quinn breaking appears at high temperatures. Furthermore, it will be shown that trapped misalignment can dynamically source the recently proposed kinetic misalignment mechanism. All the parameter space is within tantalizing reach of the experimental projects for the next decades. For instance, even Phase I of CASPEr-Electric could discover this axion.

48 pages, 21 figures. v2: Published version in JCAP

References in corpus (16)

• Ultralight scalars as cosmological dark matter
• Discovering the QCD Axion with Black Holes and Gravitational Waves
• Revisiting the bound on axion-photon coupling from Globular Clusters
• Revisiting the SN1987A gamma-ray limit on ultralight axion-like particles
• Redefining the Axion Window
• Stellar Recipes for Axion Hunters
• Search for axionlike dark matter with a liquid-state nuclear spin comagnetometer
• Anomalous solutions to the strong CP problem
• The photo-philic QCD axion
• An even lighter QCD axion
• Search for axion-like dark matter using solid-state nuclear magnetic resonance
• The impact of ultra-light axion self-interactions on the large scale structure of the Universe
• Lattice QCD for Cosmology
• $\theta$-dependence of light nuclei and nucleosynthesis
• Dynamical axion misalignment with small instantons
• Heavy axion in asymptotically safe QCD

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