Testing standard-model extensions with isotope shifts in few-electron ions

When collecting spectroscopic data on at least four isotopes, nonlinearities in the King plot are a possible sign of physics beyond standard model. In this work, an improved approach to search for hypothetical new interactions with isotope-shift spectroscopy few-electron ions is presented. Careful account taken small nuclear corrections energy levels and gyromagnetic factors, which cause deviations from linearity within model hence source confusion. approach, experimental nonlinearity not compared vanishing prediction leading order, but calculated full contribution nonlinearity. This makes searching beyond-the-standard-model analysis high-precision regime, avoiding The bounds can be set parameters remain limited by uncertainties Direct comparison between theory experiment single pair isotopes advocated as more suitable ions.