Neutrino mass textures from oscillations with maximal mixing

We study the implications of neutrino oscillations with maximal mixing for the neutrino Dirac and Majorana matrices in the see-saw mechanism for three non degenerate neutrino masses. We find the form of the Dirac matrix for a structure-less Majorana matrix and, conversely, the structure of the Majorana matrix if the Dirac matrix is according to our naive intuition. We give some examples of Majorana matrices that, in a 3 x 3 context, lead to maximal mixing without too much fine tuning and cross talk with the Dirac input. (C) 1998 Elsevier Science B.V. All rights reserved.