Stringent Constraints on New Pseudoscalar and Vector Bosons from Precision Hyperfine Splitting Measurements

Abstract:

Axionlike particles and similar new pseudoscalar as well as vector bosons coupled to nucleons and electrons are predicted to lead to spin-dependent forces in atoms and ions. We argue that hyperfine structure measurements in hydrogenlike and lithiumlike charge states are a sensitive probe to this effect. Employing specific differences of these splittings reduces uncertainties due to nuclear effects in hyperfine structure calculations and measurements. Using this, we show that existing measurements on Be provide competitive limits in the region 𝑚𝜙≳100  keV
, confirming, or improving by up to a factor of 2, existing constraints for pseudoscalar couplings, depending on the nuclear model. We also find that future measurements on Cs have a further factor of 2-2.5 improved discovery potential for pseudoscalars and an order of magnitude for new vector bosons when compared with the corresponding current constraints.

C. Quint, F. HeiSSe, J. Jaeckel, L. Leimenstoll, C. H. Keitel, Z. Harman, „Stringent Constraints
on New Pseudoscalar and Vector Bosons from Precision Hyperfine Splitting Measurements“,
Phys. Rev. Lett. 136, 113001 (2026).

https://journals.aps.org/prl/abstract/10.1103/rvt1-93v2

Related to Project B02