2024/12/13 by Alexander Wilzewski, Wilzewski, A., L. Huber +81 · 6 citations
Physics and Astronomy · #Nuclear physics research studies #Quantum Chromodynamics and Particle Interactions #Atomic and Molecular Physics
paper · pdf · doi:10.48550/arxiv.2412.10277
Nonlinearities in King plots (KP) of isotope shifts (IS) can reveal the\nexistence of beyond-Standard-Model (BSM) interactions that couple electrons and\nneutrons. However, it is crucial to distinguish higher-order Standard Model\n(SM) effects from BSM physics. We measure the IS of the transitions\n3P0~\→~3P1 in \Ca14+ and\n2S1/2 \→ 2D5/2 in \Ca+ with sub-Hz\nprecision as well as the nuclear mass ratios with relative uncertainties below\n4\×10-11 for the five stable, even isotopes of calcium\n(40,42,44,46,48\Ca). Combined, these measurements yield a\ncalcium KP nonlinearity with a significance of \∼ 900 \σ. Precision\ncalculations show that the nonlinearity cannot be fully accounted for by the\nexpected largest higher-order SM effect, the second-order mass shift, and\nidentify the little-studied nuclear polarization as the only remaining SM\ncontribution that may be large enough to explain it. Despite the observed\nnonlinearity, we improve existing KP-based constraints on a hypothetical Yukawa\ninteraction for most of the new boson masses between 10~\eV/c2 and\n107~\eV/c2.\n