Lorentz-symmetry test at Planck-scale suppression with nucleons in a spin-polarized $^{133}$Cs cold atom clock

TL;DR

This paper presents an improved theoretical model linking atomic clock frequency shifts to Lorentz-violating coefficients, enabling highly sensitive tests of Lorentz symmetry at the Planck scale using cesium atomic clocks.

Contribution

The authors develop a second-order Lorentz transformation model that accounts for nuclear structure, allowing for more precise bounds on SME coefficients from atomic clock data.

Findings

Achieved up to 12 orders of magnitude improvement in sensitivity to SME coefficients.

Set new upper limits on neutron and proton Lorentz-violating coefficients.

Demonstrated the effectiveness of the improved model in analyzing clock data.

Abstract

We introduce an improved model that links the frequency shift of the $^{133}\text{Cs}$ hyperfine Zeeman transitions $\vert F = 3, m_F> \longleftrightarrow \vert F = 4, m_F >$ to the Lorentz-violating Standard-Model Extension (SME) coefficients of the proton and neutron. The new model uses Lorentz transformations developed to second order in boost and additionally takes the nuclear structure into account, beyond the simple Schmidt model used previously in SME analyses, thereby providing access to both proton and neutron SME coefficients including the isotropic coefficient $\tilde{c}_{TT}$. Using this new model in a second analysis of the data delivered by the FO2 dual Cs/Rb fountain at Paris Observatory and previously analysed in arXiv:hep-ph/0601024v1, we improve by up to 12 orders of magnitude the present maximum sensitivities (see arXiv:0801.0287v9) on the $\tilde{c}_{Q}$, $\tilde{c}_{TJ}$ and $\tilde{c}_{TT}$ coefficients for the neutron and on the $\tilde{c}_{TT}$ coefficient for the proton, reaching respectively $10^{-20}$, $10^{-17}$, $10^{-13}$ and $10^{-15}$ GeV.