Abstract

We calculate the proton and neutron spin contributions for nuclei using semi-empirical methods, as well as a novel hybrid \emph{ab initio}/semi-empirical method, for interpretation of experimental data. We demonstrate that core-polarisation corrections to \emph{ab initio} nuclear shell model calculations generally reduce discrepancies in proton and neutron spin expectation values from different calculations. We derive constraints on the spin-dependent P,T-violating interaction of a bound proton with nucleons, which for certain ranges of exchanged pseudoscalar boson masses improve on the most stringent laboratory limits by several orders of magnitude. We derive a limit on the CPT and Lorentz-invariance-violating parameter $|\tilde{b}_{\perp}^p| < 7.6 \times 10^{-33}$ GeV, which improves on the most stringent existing limit by a factor of 8, and demonstrate sensitivities to the parameters $\tilde{d}_{\perp}^p$ and $\tilde{g}_{ D\perp}^p$ at the level $\sim 10^{-29} - 10^{-28}$ GeV, which is a one order of magnitude improvement compared to the corresponding existing sensitivities. We extend previous analysis of nuclear anapole moment data for Cs to obtain new limits on several other CPT and Lorentz-invariance-violating parameters: $\left|b_0^p \right| < 7 \times 10^{-8}$ GeV, $\left|d_{00}^p \right| < 8 \times 10^{-8}$, $\left|b_0^n \right| < 3 \times 10^{-7}$ GeV and $\left|d_{00}^n \right| < 3 \times 10^{-7}$.

Highlights

  • Field theories, which are constructed from the principles of locality, spin-statistics and Lorentz invariance, conserve the combined CPT symmetry

  • We demonstrate that core-polarisation corrections to ab initio nuclear shell model calculations generally reduce discrepancies in proton and neutron spin expectation values from different calculations

  • Due to nuclear many-body effects, the 3He/129Xe system is quite sensitive to proton interaction parameters

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Summary

Introduction

Field theories, which are constructed from the principles of locality, spin-statistics and Lorentz invariance, conserve the combined CPT symmetry. Many tests of the fundamental symmetries of nature and searches for axion, weakly interacting massive particle (WIMP) and topological defect dark matter involve couplings of the form X·sN between a field or operator X and the spin angular momentum sN of a proton (N = p) or neutron (N = n), or depend explicitly on the spin angular momenta of the nucleons involved. [65], in which experiments were performed with a 3He/129Xe comagnetometer, we derive constraints on the spin-dependent P, T -violating interaction of a bound proton with nucleons, which for certain ranges of exchanged pseudoscalar boson masses improve on the most stringent laboratory limits by several orders of magnitude. We extend our previous analysis of nuclear anapole moment data for Cs [66] to obtain new limits on several other CPT and Lorentz-invariance-violating parameters

Nuclear theory
Section II: comagnetometer experiments
Application III: tests of fundamental symmetry
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