Minimal flavour violating extensions of the seesaw

A minimal flavour violation hypothesis for leptons can be implemented essentially in two ways that are compatible with the type-I seesaw with three singlet neutrinos N, and that satisfy the requirement that all lepton flavor violating (LFV) effects can be expressed in terms of low energy observables. One is based on the flavor group SU(3)e×SU(3)ℓ×O(3)N and is CP conserving. The other is based on SU(3)e×SU(3)ℓ+N and allows for CP violation. I review the main features of the two schemes and point out their different implications for LFV observables.