Probing short-distance modifications of gravity via spin-independent and spin-dependent effects in muonic atoms
Year: 2026
Type: article
Abstract: Spectroscopy of muonic atoms provides a powerful probe for new short-range interactions predicted by theories beyond the Standard Model (SM). In this work, we derive new constraints on both spin-independent and spin-dependent non-Newtonian gravity by leveraging the outstanding sensitivity of these systems. For spin-independent Yukawa-type forces, we analyze two complementary approaches: the $$2S-2P$$ 2 S - 2 P Lamb shift in the muonic helium-4 ion and the deuteron–proton squared charge radii difference obtained from the muonic hydrogen–deuterium isotope shift. The found constraints have reached a competitive level at sub-picometer scales, with the isotope shift method yielding the most stringent bounds for the entire sub-nanometer range and significantly surpassing limits derived exclusively from electronic atom spectroscopy for $$\lambda \lesssim 10^{-12}\text { m}$$ λ ≲ 10 - 12 m . For spin-dependent effects, we analyze the influence of the gravitational spin–orbit coupling on the $$2P_{3/2}-2P_{1/2}$$ 2 P 3 / 2 - 2 P 1 / 2 fine-structure splitting in muonic helium, establishing new limits on post-Newtonian parameters. These bounds are shown to be more restrictive than those from other leading experimental techniques for ranges $$\lambda \lesssim 10^{-11}\text { m}$$ λ ≲ 10 - 11 m . Our findings highlight the widespread usefulness of muonic atoms in exploring new fundamental physics at short-distance scales.
Authors: J. E. J. Matias, A. S. Lemos, F. Dahia
Language: English
Topic: Atomic and Molecular Physics
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,890
Awards: G3690646728, G4419633615
OpenAlex ID: W7140205271