Multiple-isotope comparison for determining 0νββ mechanisms

We present a technique for estimating the number of future 0νββ results using several distinct nuclei to optimize the physics reach of upcoming experiments. We use presently available matrix-element calculations and simulated sets of predicted 0νββ measured rates in multiple isotopes to estimate the required precision and number of experiments to discern the underlying physics governing the mechanism of the process. Our results indicate that three (four) experimental results with total uncertainty (statistical, systematic, theoretical) of less than ∼20% (∼40%) can elucidate the underlying physics. If the theoretical (i.e. matrix-element) uncertainty contribution is below ∼18%, then three or four experimental results of ∼20% precision (statistical and systematic) are required. These uncertainty goals can be taken as guidance for the upcoming theoretical and experimental programs.