Isotope shift spectroscopy for enhanced bounds on physics beyond the Standard Model

We consider the impact of combining precision spectroscopic measurements made in atomic hydrogen with similar measurements made in atomic deuterium on the search for physics beyond the Standard Model. Specifically we consider the wide class of models that can be described by an effective Yukawa-type interaction between the nucleus and the electron. It is possible, using existing data, to set bounds on new light-mass bosons that are orders of magnitude more sensitive than those set using a single isotope only, provided the interaction couples differently to the deuteron and proton. Further enhancements of these bounds would be made possible by extending the current measurements of the isotope shift of the 1s_1/2 -- 2s_1/2 transition frequency to that of a transition between the 2s_1/2 state and a Rydberg s-state. We also discuss the impact of a new physics interaction on the isotope shift in helium.