Bonn 2025 – wissenschaftliches Programm

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SYPM: Symposium Precision Measurements at the Intersection of Atomic and Nuclear Physics

SYPM 1: Precision Measurements at the Intersection of Atomic and Nuclear Physics

SYPM 1.1: Hauptvortrag

Mittwoch, 12. März 2025, 14:30–15:00, HS 1+2

Probing new bosons and nuclear structure with ytterbium isotope shifts — •Tanja Mehlstäubler^1,2, Chih-Han Yeh¹, Henning Fürst¹, and Laura Dreissen¹ — ¹Physikalisch-Technische Bundesanstalt, Braunschweig, Germany — ²Institut fuer Quantenoptik, Leibniz Universitaet Hannover, Germany

High precision spectroscopy in trapped cold ions enables sensitive tests of the Standard Model and the search for new physics. For example, isotope-shift spectroscopy is a sensitive probe for nuclear structure and fifth forces mediated by a new boson that couples electrons and neutrons. Deviations from a linear relation in the King-plot analysis can indicate new physics or higher-order SM effects. This powerful technique revealed for the first time King-plot nonlinearities in Yb. We present two-orders-of-magnitude improved spectroscopic measurements in all five stable spinless isotopes of this element. The transition frequency of the forbidden ²S_1/2 to ²D_5/2 and ²S_1/2 to ²F_7/2 transitions are determined with an accuracy of 6 and 16 Hz, respectively, yielding isotope shifts with a relative precision as low as 10⁻⁹. We combine these spectroscopic results with new mass measurements with a relative precision of a few 10⁻¹². With this, we can extract a new bound on the mass and coupling strength of the potential new bosons. The results are also used to investigate higher-order nuclear structure effects along a chain of Yb isotopes. In combination with ab initio nuclear structure calculations, this provides a window to nuclear deformation and nuclear charge distributions along isotopic chains towards exotic, neutron-rich nuclei.

Keywords: Isotope Shifts; Optical Clocks; Trapped Ions; Test of Fundamental Physics