Option of light righthanded neutrinos avoiding oscillations
  A new explicit model of neutrino texture is presented, where in the overall 6x6 mass matrix the lefthanded and righthanded Majorana 3x3 components are diagonal with equal entries of opposite sign, while the Dirac 3x3 component is given as a diagonal hierarchical structure (possibly similar to the charged lepton and quark 3x3 mass matrices) deformed by the popular nearly bimaximal 3x3 mixing matrix. Then, all neutrino masses are light and m_1 = -m_4, m_2 = -m_5, m_3 = -m_6. The resulting neutrino oscillation formulae are identical with those working in the effective texture of three active neutrinos, based on this nearly bimaximal mixing matrix. Three (conventional) sterile neutrinos do not oscillate and so, are strictly decoupled. The suggested LSND effect vanishes. The not observed Chooz oscillation effect is consistently negligible. 
Wojciech Krolikowski