Improved limits on the spin- and velocity-dependent exotic interaction in the micrometer range

TL;DR

This study experimentally searches for spin- and velocity-dependent exotic interactions at micrometer scales, setting new upper limits on their coupling constants by using a microfabricated spin source and sensitive force measurements.

Contribution

The paper introduces a novel experimental approach to constrain exotic interactions at micrometer ranges using a periodically driven spin source and harmonic analysis.

Findings

No exotic interaction signal detected within the measurement sensitivity.

Established new upper limits on the coupling constant below 10 μm, with $f_{4+5} \,\le 2.2\times 10^{-9}$ at 2.1 μm.

Demonstrated effective separation of exotic signals from spurious forces using harmonic analysis.

Abstract

Searching for the exotic interactions beyond the Standard Model of particle physics may solve some of the current puzzles in physics. Here the authors experimentally explore a spin- and velocity-dependent exotic interaction between the nucleons in a gold sphere and the electrons in a spin source in the micrometer range. The microfabricated spin source provides periodically varying spin density of electrons, resulting in a periodic exotic field. A cantilever glued with a gold sphere is used to measured the force acting on the gold sphere by the spin source. The spin source is driven to oscillate, and then the imaginary part of the signal is extracted at the 10th harmonic of the oscillation frequency, which effectively separates the exotic interaction from the spurious forces commonly present in such short-range measurements. No signal of the exotic interaction is observed, then new limits on the coupling constant are set in an interaction range below 10 $\mu$m, with $f_{4+5} \le 2.2\times 10^{-9}$ at 2.1 $\mu$m.