Nuclear Matrix Elements for Neutrinoless Double Beta Decay

Nuclear-structure theory has advanced quickly in recent years. The field is now at the point at which an accurate calculation of the nuclear matrix elements governing neutrinoless double-beta decay should soon be possible. After reviewing double-beta decay and the importance of upcoming experiments for neutrino and particle physics, I describe some of the most promising theoretical many-body methods and their application to the nuclear matrix-element problem.