Towards a Global Search for New Physics with Isotope Shifts

TL;DR

This paper introduces a new framework for analyzing isotope shift data across multiple elements to improve the search for new physics and understand nuclear structure, accounting for correlations and uncertainties.

Contribution

The paper presents the kifit framework, enabling combined analysis of isotope shift data from various elements with correlation considerations for the first time.

Findings

The kifit framework effectively analyzes linear and nonlinear King plots.

It quantifies uncertainties in isotope shift measurements.

Recommendations are provided for future experiments to enhance sensitivity.

Abstract

Isotope shifts have emerged as a sensitive probe of new bosons that couple to electrons and neutrons, and of nuclear structure. The recent Hz- or even sub-Hz-level isotope shift measurements across different elements call for a global assessment of all available data. In this work, we present the fit framework kifit that for the first time enables a combined analysis of isotope shift data from several elements, taking into account correlations. We provide a thorough comparison of analytical methods and the fit to analyse linear and nonlinear King plots and quantify their uncertainties. Finally, we provide recommendations for future measurements that could enhance the sensitivity to new physics and offer new insights into nuclear structure.