Abstract:
Historically, precise atomic spectroscopy has led to new physics in many instances. Precision low-energy experiments may thus supplement high-energy and astrophysical approaches. It has been proposed to measure the isotope shifts (ISs) in ions to probe new physics using King plots [1], two-dimensional graphs that map the measured ISs [2]. The Standard Model (SM) predicts in the leading order that the points in a King plot should lie on a straight line. Departure from such linearity is unambiguously observed in our recent experiments with narrow optical transitions in trapped ions [3]. However, the contribution of higher-order corrections to the non-linearity within the SM complicates the test. The sources of the observed violation should be examined carefully to decouple the SM corrections arising from nuclear physics from possible new-physics contributions.
Here I will present our latest experimental and theoretical efforts to observe the non-linearity, identify its physical origin, and obtain the bound on dark boson-mediated interaction as a particular type of new physics that is of increasing interest. Future works will be discussed subsequently.
[1] J. C. Berengut et al., PRL 120 091801 (2018); V. V. Flambaum, A. J. Geddes, and A. V. Viatkina, PRA 97 032510 (2018); C. Delaunay et al., PRD 96 093001 (2017)
[2] W. H. King, Isotope Shifts in Atomic Spectra (Plenum Press, New York, 1984)
[3] J. Hur* et al., PRL 128, 163201 (2022)