Symplectic Symmetry of the Neutrino Mass and the See-Saw Mechanism
  We investigate the algebraic structure of the most general neutrino mass Hamiltonian and place the see-saw mechanism in an algebraic framework. We show that this Hamiltonian can be written in terms of the generators of an Sp(4) algebra. The Pauli-Gursey transformation is an SU(2) rotation which is embedded in this Sp(4) group. This SU(2) also generates the see-saw mechanism. 
A.B. Balantekin (Wisconsin U., Madison and Max-Planck-Institute,   Heidelberg) and N. Ozturk (U. Wisconsin)