Majorana neutrino mass constraints in the landscape of nuclear matrix elements

We discuss up-to-date constraints on the Majorana neutrino mass m beta beta from neutrinoless double beta and MAJORANA (76Ge) and CUORE (130Te). Best fits and upper bounds on m beta beta are explored in the general landscape of nuclear matrix elements (NME), as well as for specific NME values obtained in representative nuclear models. By approximating the likelihood of 0v beta beta signals through quadratic forms, the analysis of separate and combined isotope data becomes exceedingly simple, and allows us to clarify various aspects of multi-isotope data combinations. In particular, we analyze the relative impact of different data in setting upper bounds on m beta beta, as well as the conditions leading to nonzero m beta beta at best fit, for variable values of the NMEs. Detailed results on m beta beta from various combinations of data are reported in graphical and numerical form. Implications for future 0v beta beta data analyses and NME calculations are briefly discussed.