Dynamical Yukawa Couplings

Understand

The matter content of the Standard Model admits a global symmetry due to the generational structure of the spectrum respected by all interactions except for fermion couplings to the Higgs doublet.

• This symmetry is identified as the largest possible global symmetry of the free theory and extended to the case of massive neutrinos.
• The violation of such symmetry is then assumed dynamical and the value of the Yukawa couplings is fixed by a variational principle.
• This ansatz yields compelling results: Quark Yukawas naturally accommodate hierarchical masses and small mixing whereas Lepton Yukawas exhibit a hierarchical pattern for charged leptons and simultaneously degeneracy in the neutrino sector correlated with large mixing and Majorana phases.