Narrow and ultra-narrow transitions in highly charged Xe ions as probes of fifth forces

TL;DR

This paper explores using highly charged xenon ions and their narrow optical transitions to detect hypothetical fifth forces, proposing new spectroscopic methods and identifying a potential clock transition.

Contribution

It reports the discovery and measurement of twelve magnetic-dipole lines in highly charged Xe ions and identifies a promising clock transition at 764.8753 nm for fifth-force detection.

Findings

Twelve magnetic-dipole lines measured in highly charged Xe ions.

Identified a 764.8753 nm E2 transition with 500 s lifetime as a clock candidate.

Analyzed sensitivity to fifth-forces and suppression of Standard Model effects.

Abstract

Optical frequency metrology in atoms and ions can probe hypothetical fifth-forces between electrons and neutrons by sensing minute perturbations of the electronic wave function induced by them. A generalized King plot has been proposed to distinguish them from possible Standard Model effects arising from, e.g., finite nuclear size and electronic correlations. Additional isotopes and transitions are required for this approach. Xenon is an excellent candidate, with seven stable isotopes with zero nuclear spin, however it has no known visible ground-state transitions for high resolution spectroscopy. To address this, we have found and measured twelve magnetic-dipole lines in its highly charged ions and theoretically studied their sensitivity to fifth-forces as well as the suppression of spurious higher-order Standard Model effects. Moreover, we identified at 764.8753(16) nm a E2-type ground-state transition with 500 s excited state lifetime as a potential clock candidate further enhancing our proposed scheme.