Should neutrinoless double beta decay be observed it would inform us that neutrinos are Majorana in nature and that lepton-number conservation is violated, demanding a modification to the Standard Model. The lifetime provides information on the effective mass of the neutrino and thus on the absolute neutrino mass scale. However, such information is only meaningful if the nuclear matrix elements are reliably understood. Present theoretical calculations predict values that vary by factors of 2-3 for any given candidate. These uncertainties translate to as much as an order of magnitude in the half-life and could have significant implications in the design of experiments searching for neutrinoless double beta decay. I will discuss a program of measurements made over the last decade that have provided information on nuclear-structure properties, such as the microscopic population of valence orbitals by nucleons, that effectively define the ground-state wave functions of these nuclei. This information can and has been used to constrain calculations of the nuclear matrix element. The discussion will focus primarily on experimental data and theoretical calculations relating to the 76Ge→76Se, 130Te→130Xe, and 136Xe→136Ba systems, the three prime candidates currently under investigation.

Argonne Physics Division Colloquium Schedule