Investigation of the Gravitational Potential Dependence of the Fine-Structure Constant Using Atomic Dysprosium

TL;DR

This study used atomic dysprosium to test if the fine-structure constant varies with gravitational potential, setting new laboratory limits and constraining related fundamental mass ratios.

Contribution

It provides the first limits on how electron and quark masses vary with gravitational potential using dysprosium atomic transitions.

Findings

Established the best laboratory limit on the variation of the fine-structure constant.

Derived new constraints on the variation of electron and quark masses in gravitational fields.

Measured the parameter $k_eta$ with high precision over an eight-month period.

Abstract

Radio-frequency E1 transitions between nearly degenerate, opposite parity levels of atomic dysprosium were monitored over an eight month period to search for a variation in the fine-structure constant. During this time period, data were taken at different points in the gravitational potential of the Sun. The data are fitted to the variation in the gravitational potential yielding a value of $(-8.7 \pm 6.6) \times 10^{-6}$ for the fit parameter $k_\alpha$. This value gives the current best laboratory limit. In addition, our value of $k_{\alpha}$ combined with other experimental constraints is used to extract the first limits on k_e and k_q. These coefficients characterize the variation of m_e/m_p and m_q/m_p in a changing gravitational potential, where m_e, m_p, and m_q are electron, proton, and quark masses. The results are $k_e = (4.9 \pm 3.9) \times 10^{-5}$ and $k_q = (6.6 \pm 5.2) \times 10^{-5}$.