Constraint on an Exotic Parity-Odd Spin- and Velocity-Dependent Interaction with Atom Interferometer

Area of Science:

• Atomic physics
• Fundamental interactions
• Precision measurements

Background:

• Testing fundamental symmetries like parity is crucial for understanding particle physics.
• Spin- and velocity-dependent (SVD) interactions are predicted by some extensions to the Standard Model.
• Previous experiments have sought to constrain these interactions using various methods.

Purpose of the Study:

• To perform a high-precision atom-interferometric test of the parity-odd SVD interaction.
• To probe the interaction between spin-polarized protons and unpolarized nucleons.
• To improve the precision of tests for the universality of free fall.

Main Methods:

• Utilized a Bragg atom interferometer with Rubidium-87 (⁸⁷Rb) atoms.
• The unpaired proton in ⁸⁷Rb nuclei served as the test spin.
• Employed differential acceleration measurements and a shielded laboratory environment to minimize systematic errors and enhance sensitivity to SVD interactions.

Main Results:

• Achieved a test precision for the universality of free fall of 9.2×10⁻⁹, a tenfold improvement over previous experiments.
• Provided a new, stringent constraint on the coupling of the SVD interaction to spin-polarized protons: |g_{A}^{p}g_{V}^{N}|≤6.5×10⁻³² at λ=10 m.
• Demonstrated a substantial sensitivity improvement for probing new physics.

Conclusions:

• The experiment successfully constrained parity-odd SVD interactions with unprecedented precision.
• Atom interferometry with polarized atoms offers a powerful new tool for testing fundamental physics.
• The findings open new avenues for exploring physics beyond the Standard Model.