Solar Neutrino Problem in Seesaw Model

A specific texture for the Dirac and Majorana mass matrices in the seesaw model leading to a pair of almost degenerate neutrinos is discussed. This texture can be obtained by imposing a global U(1) symmetry. This model could solve the solar neutrino problem through the MSW mechanism and offer the hot component of the dark matter of the universe which requires Σm_vi = 7 eV.