Relating Small Neutrino Masses and Mixing

Experiments on neutrino oscillations have uncovered several small parameters, theta(13) being a prominent one. Others are the solar mass splitting vis-a-vis the atmospheric one and the deviation of theta(23) from maximal mixing. In this talk, we elaborate on a neutrino mass model based on the see-saw mechanism in which the mixing angles to start with are either vanishing (theta(13) and theta(12)) or pi/4 (theta(23)). The atmospheric mass splitting is taken as a part of this initial structure but the solar splitting is absent. A perturbative contribution, originating from a Type-I see-saw, results in nonzero values of theta(13),theta(12),Delta m(solar)(2), and shifts theta(23) slightly from pi/4, interrelating them all. The model incorporates CP-violation, the phase delta being close to 3 pi/2 for (a) quasidegeneracy or (b) inverted mass ordering. It will be put to test as the neutrino parameters get better determined.