Fermion Flavor in Soft-Wall AdS

TL;DR

This paper develops a formalism for modeling multiple fermion generations in a soft-wall warped extra dimension, deriving analytical solutions in special cases and numerically analyzing the general three-generation scenario, showing it reproduces realistic fermion spectra.

Contribution

It extends single-generation analyses to multiple generations in soft-wall models, providing analytical solutions for special cases and a numerical routine for the general case.

Findings

Fermion mass spectrum resembles standard model quarks and leptons.

Highly degenerate couplings to Kaluza-Klein gauge bosons.

Soft-wall models share attractive features with hard-wall models.

Abstract

The formalism for modeling multiple fermion generations in a warped extra dimension with a soft-wall is presented. A bulk Higgs condensate is responsible for generating mass for the zero-mode fermions but leads to additional complexity from large mixing between different flavors. We extend existing single-generation analyses by considering new special cases in which analytical solutions can be derived and discuss flavor constraints. The general three-generation case is then treated using a simple numerical routine. Assuming anarchic 5D parameters we find a fermion mass spectrum resembling the standard model quarks and leptons with highly degenerate couplings to Kaluza-Klein gauge bosons. This confirms that the soft-wall model has similar attractive features as that found in hard-wall models, providing a framework to generalize existing phenomenological analyses.