# Probing new light force-mediators by isotope shift spectroscopy

## TL;DR

This paper proposes using isotope shift spectroscopy to detect new light force-mediators, developing a formalism to interpret data as bounds on new physics, and demonstrating potential for high sensitivity in future experiments.

## Contribution

It introduces a novel formalism for interpreting isotope shift data as bounds on new light bosons, independent of nuclear effects, and applies it to existing and future experimental data.

## Key findings

- Current Ca+ data sets bounds on new bosons.
- Projected future measurements could improve sensitivity by five orders of magnitude.
- Potential to detect bosons in the 10 keV to 10 MeV mass range.

## Abstract

In this Letter we explore the potential of probing new light force-carriers, with spin-independent couplings to the electron and the neutron, using precision isotope shift spectroscopy. We develop a formalism to interpret linear King plots as bounds on new physics with minimal theory inputs. We focus only on bounding the new physics contributions that can be calculated independently of the Standard Model nuclear effects. We apply our method to existing Ca+ data and project its sensitivity to possibly existing new bosons using narrow transitions in other atoms and ions (specifically, Sr and Yb). Future measurements are expected to improve the relative precision by five orders of magnitude, and can potentially lead to an unprecedented sensitivity for bosons within the 10 keV to 10 MeV mass range.