New Limit Set on Nuclear Schiff Moment of Europium-153
Researchers have placed a new upper limit on the nuclear Schiff moment of europium-153, constraining it to less than 1.7 × 10⁻⁸ e·fm³ at 95% confidence. The measurement was made using nuclear spin resonances in oppositely-polarized Eu³⁺ ions embedded in a crystal, a compact tabletop-scale approach. The result constrains hypothetical new physics at the TeV energy scale, complementing large particle collider experiments.
A team of physicists has reported a new experimental limit on the nuclear Schiff moment of the europium-153 nucleus, a quantity that, if nonzero, would signal CP-symmetry violation and physics beyond the Standard Model. The upper bound of |S(¹⁵³Eu)| < 1.7 × 10⁻⁸ e·fm³ (95% confidence level) was obtained by measuring nuclear spin resonances in two ensembles of oppositely-polarized ¹⁵³Eu³⁺ ions implanted in a yttrium orthosilicate (Y₂SiO₅) crystal. The use of octupolar nuclei — nuclei with a non-spherical charge distribution — in a millimeter-scale solid-state crystal represents a distinct experimental strategy compared to atomic or molecular beam experiments. By comparing the spin precession frequencies of the two oppositely-polarized ensembles, the experiment is sensitive to a parity- and time-reversal-violating energy shift that would arise from a nonzero Schiff moment. The result demonstrates that compact crystal-based systems can probe new physics at TeV energy scales, the same regime explored by large colliders such as the LHC.
What's missing
The paper does not yet report peer review status (it is a preprint). Key open questions include how this limit compares quantitatively to existing Schiff moment limits from other nuclei (e.g., ¹⁹⁹Hg or ²²⁵Ra), what specific beyond-Standard-Model scenarios (e.g., QCD axion, supersymmetric CP violation) are most tightly constrained by this result, and what systematic uncertainties dominate the measurement.
What different sources said
- arXiv physicsCenter
Limit on the nuclear Schiff moment of europium-153
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