Special Physics Seminar

nEXO and the future of neutrinoless double beta decay

Brian Lenardo

SLAC National Accelerator Laboratory
Stanford University

The discovery that neutrinos have nonzero, but inexplicably small, masses is a hint that these particles may hold a key to unlocking physics beyond the Standard Model. In this talk, I will discuss the search for neutrinoless double beta decay (0νββ), a proposed form of radioactive decay which is only possible if neutrinos and antineutrinos are their own antiparticles. Such a discovery would immediately demonstrate new physics, specifically establishing a) violation of lepton number conservation, currently thought to be a fundamental symmetry of particle interactions, b) the generation of neutrino masses by a mechanism other than the Higgs, and c) possible connections between neutrino interactions and the dominance of matter over antimatter in the universe. These exciting possibilities have motivated a worldwide program to search for 0νββ using a variety of experimental techniques. In this talk, I will describe the next generation of these experiments, focusing in particular on the nEXO experiment. nEXO is designed to push two orders of magnitude beyond the reach of current experiments, which requires the ability to detect just one 0νββ decay event per year in a volume of ~10²⁸ atoms. I will describe how nEXO will meet the stringent low-background requirements needed to achieve this exquisite sensitivity, then discuss how its unique capabilities may enable other possible science in the field of particle astrophysics. I will close with a discussion on scaling up the techniques used by nEXO to enable beyond-the-next-generation searches for new physics.