Experimental Limits on Exotic Spin and Velocity Dependent Interactions Using Rotationally Modulated Source Masses and...

Area of Science:

• Particle Physics
• Beyond Standard Model Physics
• Experimental Physics

Background:

• Theories beyond the Standard Model predict new light particles mediating weak interactions.
• These interactions can manifest as exotic spin-velocity-dependent forces between electrons and nucleons.
• Previous experimental constraints on such interactions were limited.

Purpose of the Study:

• To search for and constrain exotic spin-velocity-dependent interactions between electrons and nucleons.
• To test predictions from theories beyond the Standard Model.
• To improve existing experimental upper limits on specific coupling constants.

Main Methods:

• Utilized a novel experimental scheme involving rotationally modulated source masses (∼6 kg) at 20 Hz.
• Employed an array of four atomic magnetometers for enhanced statistics and common-mode noise cancellation.
• Applied high-precision numerical integration and a [+1,-3,+3,-1] weighting method after reversing rotation direction to isolate signals and mitigate drift.

Main Results:

• Established new upper limits on the product of vector and axial-vector couplings: |g_{V}^{N}g_{A}^{e}| < 2.1 × 10^{-34}.
• Set new upper limits on the product of axial-vector and axial-vector couplings: |g_{A}^{N}g_{A}^{e}| < 2.4 × 10^{-22}.
• Achieved significant improvements over previous constraints: over 4 orders of magnitude for vector-axial-vector and 2 orders for axial-axial interactions at a 10 m range.

Conclusions:

• The experiment provides the most stringent constraints to date on exotic spin-velocity-dependent electron-nucleon interactions.
• These results significantly narrow the parameter space for new light particles and weak interactions beyond the Standard Model.
• The employed experimental technique demonstrates a powerful method for probing subtle, velocity-dependent forces.