We propose an SO(10) scheme where \neu masses can simultaneously explain the solar and atmospheric neutrino deficits, together with a hot dark matter component. In our scheme the νe, νμ, and ντ are approximately degenerate with a mass of about 2 eV, which can lead to an observable neutrinoless double beta decay rate. The model is based on a realization of the seesaw mechanism in which the main contribution to the light \neu masses is universal, due to a suitable SU(2) horizontal symmetry, while the splittings between \ne and \nm explain the solar \neu deficit and that between \nm and \nt explain the atmospheric \neu anomaly.
Ioannisian, Ara Furtado Valle, José Wagner 1994 SO(10) grand unification model for degenerate neutrino masses Physics Letters B 332 1-2 93 99
