Search for Postinflationary QCD Axions with a Quantum-Limited Tunable Microwave Receiver

Area of Science:

• * Particle Physics and Cosmology
• * Dark Matter Searches

Background:

• * Cosmological axions are hypothetical particles proposed as a dark matter candidate.
• * The axion mass range around 42 μeV is a target for ongoing experimental searches.
• * Previous experiments have constrained axion properties, motivating further investigation.

Purpose of the Study:

• * To search for cosmological axions within a specific mass range (m_a ≃ 42 μeV).
• * To set new experimental limits on the axion-photon coupling strength.
• * To test the viability of hadronic axion models in the post-inflationary dark matter scenario.

Main Methods:

• * Utilized the QUAX (Quantum Appreciative Xenon) experimental apparatus, a haloscope.
• * Employed a 1-liter tunable cavity within a strong 8 Tesla magnetic field.
• * Implemented a quantum-limited detection chain for high sensitivity.

Main Results:

• * Scanned a frequency range of 38 MHz centered at 10.2 GHz.
• * Established limits on axion-photon coupling at the 10⁻¹⁴ GeV⁻¹ level.
• * No axion signal candidate was observed within the scanned region.

Conclusions:

• * The experiment successfully constrained axion properties and ruled out viable hadronic axion models for m_a > 40 μeV.
• * This result impacts the search for axion dark matter in the post-inflationary paradigm.
• * Further searches are needed to explore other axion mass ranges and models.