Probing new bosons and nuclear structure with ytterbium isotope shifts

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.