Natural Realizations of the Seesaw Mechanism in Miniwarped Minimal SO(10)
The minimal supersymmetric SO(10) grand unified theory (GUT) models with 10, 126, and 210 Higgs and only renormalizable couplings have been shown to provide a simple way to understand the neutrino mixings as well as the ratio Δm²⌄⊙/Δm²⌄A in terms of quark mixing parameter θ⌄Cabibbo, provided neutrino masses are described by a type II seesaw formula. However, in this minimal picture, it is impossible to realize type II dominance with renormalizable couplings in 4 dimensions. We show that this problem can be cured by embedding this model into a warped five dimensional space-time with warping between the Planck and the GUT scale, where both type II as well as mixed seesaw formulas can be realized in a natural manner without expanding the Higgs sector. These models also avoid the possible problem of threshold effects associated with large Higgs representations since the theory above the GUT scale is now strongly coupled.