  We propose a mechanism to generate the neutrino mixing matrix from
supersymmetric threshold corrections. Flavor violating soft breaking terms
induce flavor changing self-energies that give a finite renormalization to the
mixing matrix. The described threshold corrections get enhanced in case of
quasi-degenerate neutrino masses. In this scenario, we adjust potentially
arbitrary soft breaking parameters in a way to reproduce the observed neutrino
mixing at one loop working with non-minimal flavor violating soft parameters.
To incorporate small neutrino masses already at tree-level via a type I seesaw
mechanism, we extend the Minimal Supersymmetric Standard Model with singlet
Majorana neutrinos. The radiative corrections do not decouple with the scale of
Supersymmetry and persist when the spectrum is shifted to higher values.
Moreover, the mixing matrix renormalization with flavor-changing self-energies
is not restricted to supersymmetric theories and give similar results in any
theory with new flavor structures.
