Probing physics beyond the standard model using ultracold mercury

Searches for physics beyond the standard model (SM) range from high-energy collision experiments to low-energy table-top experiments. Cosmological phenomena suggest the existence of yet undiscovered particles, described as dark matter. Recently, it was proposed to employ high precision spectroscopy of atomic isotope shifts [Delaunay, PRD 96, 093001 (2017); Berengut, PRL 120, 091801 (2018)] to search for a new force carrier that directly couples quarks and leptons. Signatures of such new particles would emerge as nonlinearities in King plots of scaled isotope shifts on different electronic transitions.

Mercury is one of the heaviest laser-coolable elements and possesses five naturally occurring bosonic isotopes, all of which have been laser-cooled in a magneto-optical trap. We report on optimizing these trap parameters and we present our latest results of precision isotope spectroscopy in ultracold mercury on various optical transitions. Our King plot analysis of the nonlinearities indicates deviations from SM predictions.