1. Nonlinear calcium King plot constrains new bosons and nuclear properties
- Author
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Wilzewski, A., Huber, L. I., Door, M., Richter, J., Mariotti, A., Spieß, L. J., Wehrheim, M., Chen, S., King, S. A., Micke, P., Filzinger, M., Steinel, M. R., Huntemann, N., Benkler, E., Schmidt, P. O., Flannery, J., Matt, R., Stadler, M., Oswald, R., Schmid, F., Kienzler, D., Home, J., Craik, D. P. L. Aude, Eliseev, S., Filianin, P., Herkenhoff, J., Kromer, K., Blaum, K., Yerokhin, V. A., Valuev, I. A., Oreshkina, N. S., Lyu, C., Banerjee, S., Keitel, C. H., Harman, Z., Berengut, J. C., Viatkina, A., Gilles, J., Surzhykov, A., Rosner, M. K., López-Urrutia, J. R. Crespo, and Fuchs, E.
- Subjects
Physics - Atomic Physics - Abstract
Nonlinearities in King plots (KP) of isotope shifts (IS) can reveal the existence of beyond-Standard-Model (BSM) interactions that couple electrons and neutrons. However, it is crucial to distinguish higher-order Standard Model (SM) effects from BSM physics. We measure the IS of the transitions ${{}^{3}P_{0}~\rightarrow~{}^{3}P_{1}}$ in $\mathrm{Ca}^{14+}$ and ${{}^{2}S_{1/2} \rightarrow {}^{2}D_{5/2}}$ in $\mathrm{Ca}^{+}$ with sub-Hz precision as well as the nuclear mass ratios with relative uncertainties below $4\times10^{-11}$ for the five stable, even isotopes of calcium (${}^{40,42,44,46,48}\mathrm{Ca}$). Combined, these measurements yield a calcium KP nonlinearity with a significance of $\sim 900 \sigma$. Precision calculations show that the nonlinearity cannot be fully accounted for by the expected largest higher-order SM effect, the second-order mass shift, and identify the little-studied nuclear polarization as the only remaining SM contribution that may be large enough to explain it. Despite the observed nonlinearity, we improve existing KP-based constraints on a hypothetical Yukawa interaction for most of the new boson masses between $10~\mathrm{eV/c^2}$ and $10^7~\mathrm{eV/c^2}$.
- Published
- 2024