Fermion localization on thick branes

TL;DR

This paper investigates how chiral fermions can be confined on thick branes in higher-dimensional spacetimes, analyzing the conditions for localization of massless and massive modes, and the effects of brane thickness and geometry.

Contribution

It provides a detailed analysis of fermion localization on scalar thick branes, including the behavior in the thin-wall limit and the impact of different brane geometries.

Findings

Only one massless chiral mode is localized with finite wall thickness.

Chiral fermionic modes cannot be localized on dS_4 walls in M_5 spacetime.

Double walls support quasi-localized massive fermion modes.

Abstract

We consider chiral fermion confinement in scalar thick branes, which are known to localize gravity, coupled through a Yukawa term. The conditions for the confinement and their behavior in the thin-wall limit are found for various different BPS branes, including double walls and branes interpolating between different AdS_5 spacetimes. We show that only one massless chiral mode is localized in all these walls, whenever the wall thickness is keep finite. We also show that, independently of wall's thickness, chiral fermionic modes cannot be localized in dS_4 walls embedded in a M_5 spacetime. Finally, massive fermions in double wall spacetimes are also investigated. We find that, besides the massless chiral mode localization, these double walls support quasi-localized massive modes of both chiralities.