Nuclear matrix elements for neutrinoless double-beta decay

Abstract

Recent progress in nuclear-structure theory has been dramatic and a DOE-sponsored topical collaboration has formed in the US to apply new methods to the matrix elements that govern neutrinoless double-beta decay. I describe the ab initio nuclear-structure methods that are being applied, and discuss when and why traditional nuclear models are still useful. I also briefly discuss the old and vexing problem of the renormalization of the weak nuclear axial-vector coupling constant “in medium” and plans to resolve it.