Towards a new paradigm for quark-lepton unification

TL;DR

This paper proposes a new, model-independent approach to quark-lepton unification that explains mass patterns and predicts light third-generation leptons and squarks, avoiding complex flavor structures.

Contribution

It introduces a novel mechanism linking the top quark mass to light leptons and squarks, implemented within a supersymmetric SU(5) GUT framework, without extra flavor assumptions.

Findings

Successful unification achieved with the new mechanism

Light third-generation leptons and squarks predicted

No additional flavor structures beyond minimal Yukawas needed

Abstract

The quark and lepton mass patterns upset their naive unification. In this paper, a new approach to solve this problem is proposed. Model-independently, we find 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 provide 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.