Dark Matter Axion Search with HAYSTAC Phase II.

Area of Science:

• Experimental particle physics
• Cosmology and astrophysics
• Quantum measurement

Background:

• Dark matter axions are hypothetical particles proposed as a solution to the dark matter puzzle.
• The HAYSTAC (HAppy eXperiment for axion Search) experiment uses resonant cavities to detect axions.
• Squeezed states of light can reduce quantum noise below standard quantum limits.

Purpose of the Study:

• To search for dark matter axions in a specific mass range using the HAYSTAC experiment.
• To demonstrate the effectiveness of squeezed states for enhancing sensitivity in axion detection.
• To exclude specific axion coupling parameters based on experimental results.

Main Methods:

• Utilized a squeezed state receiver to achieve subquantum limited noise.
• Scanned new parameter space in the axion mass ranges of 17.28-18.44 μeV and 18.71-19.46 μeV.
• Combined new data with previous results to extend the scanned mass range to 16.96-19.46 μeV.

Main Results:

• No statistically significant evidence for an axion signal was observed in the scanned mass ranges.
• Excluded axion couplings |g_{γ}|≥2.75×|g_{γ}^{KSVZ}| and |g_{γ}|≥2.96×|g_{γ}^{KSVZ}| at the 90% confidence level.
• Achieved a total exclusion of |g_{γ}|≥2.86×|g_{γ}^{KSVZ}| at 90% confidence over the combined 2.27 μeV scanned parameter space.

Conclusions:

• The results demonstrate the capability of the squeezed state receiver to probe axion models effectively.
• The experiment achieved a significant enhancement in scan rate compared to quantum-limited experiments.
• The search sets new limits on dark matter axion properties within the explored mass range.