Oscillating Nuclear Charge Radii as Sensors for Ultralight Dark Matter

Area of Science:

• * Particle Physics
• * Astrophysics
• * Atomic Physics

Background:

• * Ultralight dark matter (UDM) interactions with quarks and gluons can affect nuclear properties.
• * Nuclear charge radius oscillations are significant for heavy elements.
• * Optical atomic clocks offer high precision for detecting subtle atomic frequency shifts.

Purpose of the Study:

• * To investigate the impact of UDM-nuclear couplings on nuclear charge radius.
• * To explore the potential of optical atomic clocks in probing UDM interactions.
• * To set bounds on scalar UDM-nuclear couplings and the QCD axion decay constant.

Main Methods:

• * Theoretical analysis of UDM coupling to quarks and gluons.
• * Utilizing specific electric octupole and quadrupole transitions in Ytterbium-171 ion (¹⁷¹Yb⁺).
• * Long-term frequency comparison of selected transitions in a single trapped ¹⁷¹Yb⁺ ion.

Main Results:

• * Demonstrated that UDM coupling induces nuclear charge radius oscillations.
• * Derived sensitivity coefficients for ¹⁷¹Yb⁺ transitions to UDM.
• * Established bounds on scalar UDM-nuclear couplings and QCD axion decay constant.

Conclusions:

• * Optical atomic clocks can probe UDM-nuclear couplings previously inaccessible.
• * Current results are competitive with existing spectroscopic limits.
• * Future studies with optical clocks promise enhanced sensitivity for UDM detection.