Effects of Dark Matter and of Space–Time Variation in Physics Constants in Atomic Phenomena

Fundamental constants—such as the fine-structure constant α, the strong-interaction scale, and particle masses—may vary in an expanding Universe. Spatial variation could help explain apparent fine tuning: we inhabit a region where the conditions permit life. Hints from quasar absorption spectra suggest a gradient in α, but decisive confirmation requires laboratory tests. Atomic clocks enable such tests and, through their exquisite stability, enable sensitive searches for new physics.

Interactions between dark matter and ordinary matter can induce temporal variation in constants. For low-mass bosonic dark matter produced after the Big Bang, the field behaves classically, yielding first-order effects in the coupling—an enormous advantage over traditional second-order responses. Using atomic clocks and Big Bang Nucleosynthesis data, existing bounds on scalar and axion dark-matter couplings to photons, electrons, quarks, and W, Z and Higgs bosons can be tightened dramatically; our analyses improved previous limits by up to 15 orders of magnitude.

Another four orders of magnitude in sensitivity may be achieved using nuclear clocks which were built recently. Atomic and nuclear clocks may also be used to search for violation of fundamental symmetries and testing of unification theories.

Separately from the ultralight sector, models of modified gravity with extra dimensions—such as the Arkani-Hamed–Dimopoulos–Dvali framework—admit extremely compact massive composite objects made from quarks or antiquarks, which may be dark-matter candidates. Detection strategies for these heavy composites will be discussed.

References:

V.V. Flambaum, Phys. Rev. Lett. 97, 092502 (2006); 117, 072501 (2016). Phys.Rev.D 112, 015003 (2025)

V. Flambaum and A. J. Mansour, Phys. Rev. Lett. 131, 113004, 2023.

Y.V. Stadnik, V. V. Flambaum, Phys. Rev. Lett. 115, 201301 (2015).