Probing Axionlike Particles and the Axiverse with Superconducting Radio-Frequency Cavities

Area of Science:

• Particle Physics
• Cosmology
• Quantum Electrodynamics

Background:

• Axionlike particles (ALPs) are hypothetical particles predicted by string theory.
• ALPs may contribute to dark matter and solve the strong CP problem.
• Existing experiments have limitations in detecting light ALPs.

Purpose of the Study:

• Propose a novel experiment to detect light axionlike particles (ALPs).
• Achieve sensitivity to ALPs independent of their dark matter contribution.
• Provide a guaranteed path to observe the Euler-Heisenberg term in low-energy QED.

Main Methods:

• Utilize superconducting radio-frequency (SRF) cavities.
• Exploit cubic nonlinearities in Maxwell's equations sourced by off-shell ALPs.
• Pump the cavity at specific frequencies (ω1 and ω2) to detect power at 2ω1±ω2.

Main Results:

• The proposed SRF cavity experiment offers superior sensitivity compared to existing methods like OSQAR.
• The setup allows for detection of light ALPs independent of their cosmic dark matter density.
• Potential for the first observation of the Euler-Heisenberg term in low-energy QED.

Conclusions:

• The proposed experiment provides a novel and sensitive method for ALP detection.
• This approach can probe fundamental physics, including QED effects below the electron mass.
• The experiment offers a clear path to increasing sensitivity for future ALP searches.