Probing new bosons and nuclear structure with ytterbium isotope shifts

TL;DR

This paper reports high-precision isotope shift measurements in ytterbium ions, introduces a new method for nuclear charge distribution analysis, and uses King plot analysis to constrain potential new physics beyond the Standard Model.

Contribution

It presents a novel technique for extracting higher-order nuclear charge distribution changes and applies it to benchmark nuclear structure calculations and search for new forces.

Findings

Achieved 4×10^{-12} precision in mass-ratio measurements of Yb$^{42+}$ ions.

Performed isotope-shift measurements with 4×10^{-9} precision across multiple Yb isotopes.

Set bounds on a hypothetical fifth force coupling to electrons and neutrons.

Abstract

In this Letter, we present mass-ratio measurements on highly charged Yb$^{42+}$ ions with a precision of $4\times 10^{-12}$ and isotope-shift measurements on Yb$^{+}$ on the $^{2}$S$_{1/2}$ $\to$ $^{2}$D$_{5/2}$ and $^{2}$S$_{1/2}$ $\to$ $^{2}$F$_{7/2}$ transitions with a precision of $4\times 10^{-9}$ for the isotopes $^{168,170,172,174,176}$Yb. We present a new method that allows us to extract higher-order changes in the nuclear charge distribution along the Yb isotope chain, benchmarking ab-initio nuclear structure calculations. Additionally, we perform a King plot analysis to set bounds on a fifth force in the keV$/c^2$ to MeV$/c^2$ range coupling to electrons and neutrons.