Unified Flavor Symmetry from warped dimensions

TL;DR

This paper presents a model using warped extra dimensions with a unified flavor symmetry to explain fermion masses and mixings, highlighting how small symmetry breakings can lead to observed hierarchies and mixing patterns.

Contribution

It introduces a scenario where a common flavor symmetry in warped dimensions accounts for all SM fermion masses and mixings, including neutrinos, with hierarchical structures emerging from exponential sensitivities.

Findings

Hierarchical fermion masses arise from small symmetry breakings.

Neutrino flavor structure reflects the fundamental symmetry.

Quark sector shows effects of symmetry breaking.

Abstract

We propose a scenario which accommodates all the masses and mixings of the SM fermions in a model of warped extra-dimensions with all matter fields in the bulk. In this scenario, the same flavor symmetric structure is imposed on all the fermions of the Standard Model (SM), including neutrinos. Due to the exponential sensitivity on bulk fermion masses, a small breaking of the symmetry can be greatly enhanced and produce seemingly un-symmetric hierarchical masses and small mixing angles among the charged fermion zero-modes (SM quarks and charged leptons) and wash-out the obvious effects of the symmetry. With the Higgs field leaking into the bulk, and Dirac neutrinos sufficiently localized towards the UV boundary, the neutrino mass hierarchy and flavor structure will still be largely dominated by the fundamental flavor structure. The neutrino sector would then reflect the fundamental flavor structure, whereas the quark sector would probe the effects of the flavor symmetry breaking sector. As an example, we explore these features in the context of a family permutation symmetry imposed in both quark and lepton sectors.