Speaker
Description
Neutrinoless double-beta ($0\nu\beta\beta$) decay is a hypothetical weak-interaction process in which two nucleons inside an atomic nucleus $\beta$-decay simultaneously without emitting (anti-)neutrinos. Since the $\beta$ particles are emitted without accompanying antiparticles, the process violates lepton-number conservation and requires that neutrinos are Majorana particles, hence providing unique vistas in the physics beyond the Standard Model of particle physics. The potential to discover new physics drives ambitious experimental searches around the world. However, extracting interesting physics from the experiments relies on nuclear-theory predictions, which remain a major obstacle.
I will talk about recent advances in ab initio calculations of $0\nu\beta\beta$ decay. Since most of the $\beta\beta$-decay candidates are medium-heavy or heavy nuclei, until very recently the candidates have been out of reach of the ab initio nuclear many-body methods and the theory predictions have relied on phenomenological approaches, which tend to disagree with each other. However, with recent advances in nuclear theory, these nuclei are now becoming accessible by ab initio methods. This, combined with recent developments in an effective-field-theory approach to $0\nu\beta\beta$-decay has opened up a path towards consistent ab initio predictions for the as yet hypothetical decay.
