Quasi Goldstone fermion as a sterile neutrino

The existence of sterile neutrinos is hinted by the simultaneous presence of diverse neutrino anomalies. We suggest that the quasi Goldstone fermions (QGF's) arising in supersymmetric theory as a result of spontaneous breaking of global symmetry such as the Peccei-Quinn symmetry or She lepton number symmetry can play the role of the sterile neutrino. The smallness of the mass of QGF's (m(s) similar to 10(-3) -10 eV) can be related to the specific choice of superpotential or Kahler potential (e.g., no-scale kinetic terms for certain superfields). Mixing of QGF's with neutrinos implies R-parity violation. It can proceed via the coupling of QGF's with Higgs supermultiplets or directly with a lepton doublet. A model which accounts for the solar and atmospheric anomalies and dark matter is presented.