Toward the discovery of matter creation with neutrinoless double-beta decay

Matteo Agostini, Giovanni Benato, Jason A. Detwiler, Javier Menéndez, Francesco Vissani

Published 2022-02-03Version 1

The discovery of neutrinoless double-beta decay could soon be within reach. This hypothetical ultra-rare nuclear decay is a portal to new physics beyond the Standard Model. Its observation would constitute the discovery of a matter-creating process, corroborating leading theories of why the universe contains more matter than antimatter, and how the forces unify at high energy scales. It would also prove that neutrinos and anti-neutrinos are not two distinct particles, but can transform into each other, generating their own mass in the process. The recognition that neutrinos are not massless necessitates an explanation and has boosted interest in neutrinoless double-beta decay. The field is now at a turning point. A new round of experiments is currently being prepared for the next decade to cover an important region of parameter space. Advancements in nuclear theory are laying the groundwork to connect the nuclear decay with the underlying new physics. Meanwhile, the particle theory landscape continues to find new motivations for neutrinos to be their own antiparticle. This review brings together the experimental, nuclear theory, and particle theory aspects connected to neutrinoless double-beta decay, to explore the path toward - and beyond - its discovery.