The discovery of 0vbb has profound implications for the Standard Model, as it would proof the existence of a new type of particle, Majorana fermions, and show that lepton number conservation is violated. Moreover, it provides hints for more beyond the Standard Model physics, possibly allowing for a different mass generation mechanics (other than Higgs) and the introduction of GUT-scale heavy, right-handed neutrinos.
nEXO is a 5 tonne LXe TPC planned to search for the neutrinoless double beta decay of Xe-136 with a target half-life sensitivity of approximately 10^28 years, which is achievable through careful material selection, an improved design of the TPC and a multi-dimensional analysis and event reconstruction. MC simulations derive a sensitivity to the effective Majorana neutrino mass between 5.7 and 17.7 meV on a 90% C.L. depending on the nuclear matrix element calculation after 10 years of live time.