Scalars Gliding Through an Expanding Universe

Abstract

In this article we investigate the effects of single derivative mixing in massive bosonic fields. In the regime of large mixing, we show that this leads to striking changes of the field dynamics, delaying the onset of classical oscillations and decreasing, or even eliminating, the friction due to Hubble expansion. We highlight this phenomenon with a few examples. In the first example, we show how an axion like particle can have its number abundance parametrically enhanced. In the second example, we demonstrate that the QCD axion can have its number abundance enhanced allowing for misalignment driven axion dark matter all the way down to $f_a$ of order astrophysical bounds. In the third example, we show that the delayed oscillation of the scalar field can also sustain a period of inflation. In the last example, we present a situation where an oscillating scalar field is completely frictionless and does not dilute away in time.

arXiv comment6 + 4 pages; v2 matches version published in PRL

References in corpus (19)

• String Axiverse
• The String Dilaton and a Least Coupling Principle
• WISPy Cold Dark Matter
• New experimental approaches in the search for axion-like particles
• Cosmological Relaxation of the Electroweak Scale
• Supernova 1987A Constraints on Sub-GeV Dark Sectors, Millicharged Particles, the QCD Axion, and an Axion-like Particle
• Gauge Fields and Inflation
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• A small weak scale from a small cosmological constant
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• Axion Misalignment Driven to the Hilltop
• Relaxation of the Cosmological Constant
• Dark photon relic dark matter production through the dark axion portal
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• Magnon Inflation: Slow Roll with Steep Potentials

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• Exploring New Physics with O(keV) Electron Recoils in Direct Detection Experiments
• Hidden Photon Dark Matter Interacting via Axion-like Particles
• Cosmologically Varying Kinetic Mixing
• Supernova constraints on an axion-photon-dark photon interaction
• Adiabatic Conversion of ALPs into Dark Photon Dark Matter
• Probing the Axion-Photon-Dark Photon Interaction at Future $e^{+}{e}^{-}$ Colliders