A Phenomenological Interpretation of Atmospheric and Solar Neutrino   Oscillations
  We give a phenomenological interpretation of atmospheric and solar neutrino oscillations by considering two scenarios for the neutrino mass spectrum: (a) m_1 \ll m_2 \ll m_3 and (b) m_1 \approx m_2 \approx m_3. A new parametrization of the flavor mixing matrix, which can naturally reflect the hierarchy of lepton masses in scenario (a) and the approximate decoupling of solar and atmospheric neutrino oscillations, is highlighted. For scenario (b) an ansatz starting with flavor democracy for charged leptons and mass degeneracy for neutrinos is proposed, and two different symmetry breaking possibilities with ``maximal calculability'' are discussed. Finally we point out that possible (\sin^2 2\theta, \Delta m^2) parameter-space correlation should seriously be taken into account in future analyses of neutrino oscillations. 
Zhi-zhong Xing