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Probing an ultralight QCD axion with electromagnetic quadratic interaction

7 Pith papers cite this work. Polarity classification is still indexing.

7 Pith papers citing it
abstract

The axion-gluon coupling is the defining feature of the QCD axion. This feature induces additional and qualitatively different interactions of the axion with standard model particles -- quadratic couplings. Previously, hadronic quadratic couplings have been studied and experimental implications have been explored especially in the context of atomic spectroscopy and interferometry. We investigate additional quadratic couplings to the electromagnetic field and electron mass. These electromagnetic quadratic couplings are generated at the loop level from threshold corrections and are expected to be present in the absence of fine-tuning. While they are generally loop-suppressed compared to the hadronic ones, they open up new ways to search for the QCD axion, for instance via optical atomic clocks. Moreover, due to the velocity spread of the dark matter field, the quadratic nature of the coupling leads to low-frequency fluctuations in any detector setup. These distinctive low-frequency fluctuations offer a way to search for heavier axions. We provide an analytic expression for the power spectral density of this low-frequency background and briefly discuss experimental strategies for a low-frequency background search.

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representative citing papers

Stellar Superradiance and Low-Energy Absorption in Dense Nuclear Media

hep-ph · 2025-12-15 · unverdicted · novelty 6.0

Collective nucleon scattering in neutron-star matter suppresses the effective absorption of ultralight bosons at the long wavelengths relevant for superradiance, weakening the link between stellar cooling bounds and superradiant instability rates.

$\phi$-Dwarfs: White Dwarfs probe Quadratically Coupled Scalars

hep-ph · 2025-09-29 · unverdicted · novelty 6.0

White dwarf mass-radius data exclude large parameter space for ultralight scalars quadratically coupled to fermions by predicting forbidden radius gaps and mass shifts toward the Chandrasekhar limit or altered maximum masses.

Nelson-Barr ultralight dark matter

hep-ph · 2024-05-10 · unverdicted · novelty 6.0

Nelson-Barr mechanism yields ultralight scalar dark matter inducing time-periodic variation in CKM matrix elements, distinguishable from QCD axion and detectable via nuclear clocks.

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