Mass matrix for atmospheric, solar, and LSND neutrino oscillations - art. no. 013003

We construct a mass matrix for the four neutrino flavors, three active and one sterile, needed to fit oscillations in all three neutrino experiments: atmospheric, solar, and LSND, simultaneously. It organizes the neutrinos in to two doublets whose central values are about 1 eV apart, and whose splitt ings are of the order of 10(-3) eV. Atmospheric neutrino oscillations are d escribed as maximal mixing within the upper doublet, and solar as the same within the lower doubler. Then LSND is a weak transition from one doublet t o the other. We comment on the Majorana versus Dirac nature of the active n eutrinos and show that our mass matrix can he derived from an S-2 x S-2 per mutation symmetry plus an equal splitting rule.