Variation of Fundamental Constants due to an Interaction with Ultralight Dark Matter and Constraints on the Yukawa-type Interactions mediated by Scalar Particles

An interaction with scalar or pseudoscalar (axion) dark matter may cause the space-time variation of fundamental constants, and atomic spectroscopy provides us with a method of detecting these effects. In this paper, we study the effects produced by an oscillating nuclear mass mN and nuclear radius rN in two transition ratios: the comparison of the two-photon transition in atomic Hydrogen to the results from clocks based on the hyperfine transition in ¹³³Cs, and the ratio of the two optical clock frequencies in Al⁺ and Hg⁺. The sensitivity of these frequencies ratios to changes in the nuclear mass mN and the nuclear radius rN allows us to extract, from experimental data, new limits on the variations of the proton mass, the quark mass, the QCD parameter θ and the interaction with axion dark matter. We also consider the Yukawa-type scalar field produced by the interaction of feebly interacting hypothetical scalar particles with Standard Model particles in the presence of massive bodies such as the Sun and the Moon. Using the data from the Al⁺/Hg⁺, Yb⁺/Cs and Yb⁺(E2)/Yb⁺(E3) transition frequency ratios, we place constraints on the Yukawa-type interaction of the scalar field with photons, nucleons and electrons, for a range of scalar particle masses. We also consider limits on the Einstein Equivalence Principle (EEP) violating term (c₀₀) in the Standard Model Extension (SME) Lagrangian and the dependence of fundamental constants on gravity.