Towards a new paradigm for quark-lepton unification
Résumé
The quark and lepton mass patterns upset their naive unification. In this talk, a new approach to
solve this problem is presented. Model-independently, we show that a successful unification can be
achieved. A mechanism is identified by which the large top quark mass renders its third-generation
leptonic partner very light. This state is thus identified with the electron. We then discuss a generic
dynamical implementation of this mechanism, using tree-level exchanges of vector leptons to relate
the quark and lepton flavor structures. In a supersymmetric context, this same mechanism splits
the squark masses, and third generation squarks end up much lighter than the others. Finally, the
implementation of this mechanism in SU(5) GUT permits to avoid introducing any flavor structure
beyond the two minimal Yukawa couplings, ensuring the absence of unknown mixing matrices and
their potentially large impact on FCNC.