Lorentz-Symmetry Test at Planck-Scale Suppression With a Spin-Polarized ¹³³Cs Cold Atom Clock

Area of Science:

• Atomic Physics
• Fundamental Physics
• Metrology

Background:

• Local Lorentz invariance (LLI) is a cornerstone of modern physics.
• Previous tests using ¹³³Cs atomic clocks constrained Standard Model Extension (SME) proton coefficients.
• Improved theoretical models are needed to probe neutron coefficients and isotropic effects.

Purpose of the Study:

• To perform a novel test of local Lorentz invariance (LLI) using the ¹³³Cs cold atom clock FO2.
• To extend previous LLI tests by constraining both proton and neutron SME coefficients.
• To achieve unprecedented sensitivity to SME coefficients, including the isotropic coefficient .

Main Methods:

• Utilized the FO2 ¹³³Cs cold atom clock for high-precision frequency measurements.
• Employed a second-order Lorentz transformation in the theoretical analysis.
• Incorporated a self-consistent relativistic mean field nuclear model.

Main Results:

• Derived new, stringent constraints on SME coefficients related to both protons and neutrons.
• Achieved sensitivity to the isotropic SME coefficient , previously unconstrained by laboratory tests.
• Improved existing limits on SME coefficients by up to 13 orders of magnitude.

Conclusions:

• The ¹³³Cs FO2 clock provides leading sensitivity for probing fundamental symmetries.
• This work significantly advances the search for physics beyond the Standard Model.
• The results reach suppression scales where potential signatures of Lorentz violation are expected.