Quest for a phenomenologically consistent low cutoff theory

TL;DR

This paper explores a consistent low cutoff theory within the Randall-Sundrum framework, proposing a discrete gauged symmetry to suppress dangerous operators, and predicts Dirac neutrinos with specific mass scales, aligning with observed flavor structures.

Contribution

It introduces a discrete gauged Z_N symmetry approach to address operator suppression and fermion mass hierarchies in Randall-Sundrum models, providing a phenomenologically consistent low cutoff theory.

Findings

Predicts Dirac neutrino masses around 66 meV.

Reproduces CKM and PMNS mixing structures.

Identifies flavor observables as key probes.

Abstract

The Randall-Sundrum model with the Higgs localized on the IR brane solves the gauge hierarchy problem. However, the associated low cutoff ($\Lambda \sim 10$ TeV) generically leads to unacceptably rapid nucleon decay and excessively large Majorana neutrino masses. Achieving consistency while simultaneously explaining the Yukawa hierarchy requires either a horizontal symmetry or a discrete gauged symmetry. We demonstrate that eliminating all dangerous operators within a horizontal symmetry framework must come with large and unattractive charge assignments, if possible at all. Hence, we consider an exact discrete gauged $\mathbf{Z}_N$ symmetry, with fermion mass hierarchies generated via wave function overlap. We employ this to reproduce the current Cabibbo-Kobayashi-Maskawa and Pontecorvo-Maki-Nakagawa-Sakata structures. Assuming universal five-dimensional Yukawa couplings, generation-blind profile for right-handed neutrinos and flat profile for the third generation SM doublets, it predicts Dirac neutrinos with a total mass $\sim 66$ meV. Since the $\mathbf{Z}_N$ charges must be generation blind, flavor observables serve as key probes.