Abstract: | The observation of neutrinoless double-beta decay (0${
u}{eta}{eta}$)
would show that lepton number is violated, reveal that neutrinos are Majorana
particles, and provide information on neutrino mass. A discovery-capable
experiment covering the inverted ordering region, with effective Majorana
neutrino masses of 15 - 50 meV, will require a tonne-scale experiment with
excellent energy resolution and extremely low backgrounds, at the level of
$sim$0.1 count /(FWHM$cdot$t$cdot$yr) in the region of the signal. The
current generation $^{76}$Ge experiments GERDA and the MAJORANA DEMONSTRATOR
utilizing high purity Germanium detectors with an intrinsic energy resolution
of 0.12%, have achieved the lowest backgrounds by over an order of magnitude in
the 0${
u}{eta}{eta}$ signal region of all 0${
u}{eta}{eta}$
experiments. Building on this success, the LEGEND collaboration has been formed
to pursue a tonne-scale $^{76}$Ge experiment. The collaboration aims to develop
a phased 0${
u}{eta}{eta}$ experimental program with discovery potential
at a half-life approaching or at $10^{28}$ years, using existing resources as
appropriate to expedite physics results. |