Speaker
Dr
Lior Arazi
(Ben-Gurion University of the Negev)
Description
The nature of the neutrino, namely whether it is a Dirac or Majorana fermion, is a key question with far-reaching implications in particle physics and cosmology. The most sensitive experimental probe in this respect is the search for neutrinoless double beta decay ($\beta\beta 0\nu$), which can only occur if the neutrino is its own antiparticle. A positive detection will provide a first demonstration of lepton number violation, as well as support for theories beyond the Standard Model explaining the origin and smallness of the neutrino mass, and the generation of matter-antimatter asymmetry in the Universe via leptogenesis. The importance of $\beta\beta 0\nu$ detection on the one hand, and the availability of promising experimental schemes with already proven results on the other, motivate an international, well-funded, multi-isotope approach.
A number of experiments have already constrained the $\beta\beta 0\nu$ half-life to $10^{25}-10^{26}$ years, employing masses of $\beta\beta 0\nu$ isotopes of tens to hundreds of kg. If one assumes that the underlying mechanism for $\beta\beta 0\nu$ is the exchange of light Majorana neutrinos, this corresponds to excluding effective Majorana neutrino masses slightly above the inverted mass-ordering band in the neutrino mass parameter space. The next generation of experiments aims to fully explore the inverted mass ordering region, which requires sensitivities to half-lives of the order of $10^{27}-10^{28}$ years. This, in turn, necessitates tonne-scale masses of the $\beta\beta 0\nu$ isotopes and an order-of-magnitude improvement in background rejection. This talk will review the different technologies employed by the main $\beta\beta 0\nu$ experiments, their present status and plans for tonne-scale searches, discussing, in particular, their key merits and respective challenges.
Primary author
Dr
Lior Arazi
(Ben-Gurion University of the Negev)
