Significant neutrinoless double beta decay with quasi-Dirac neutrinos
  A significant signal of neutrinoless double beta decay can be consistent with the existence of light quasi-Dirac neutrinos. To demonstrate this possibility, we consider a realistic model where the neutrino masses and the neutrinoless double beta decay can be simultaneously generated after a Peccei-Quinn symmetry breaking. 
Pei-Hong Gu
hep-ph