Bulk phantom fields, increasing warp factors and fermion localisation

TL;DR

This paper presents an exact thick brane solution with an increasing warp factor generated by a bulk phantom scalar field, demonstrating fermion localization without extra interactions and analyzing the effects of Yukawa coupling on fermion spectra.

Contribution

It introduces a new exact solution with an increasing warp factor using a phantom scalar field, enabling fermion localization without additional forces.

Findings

Fermions can be localized on the brane with an increasing warp factor.

Yukawa coupling alters fermion mass spectrum and wave functions.

Exact solutions for localized massive fermions are provided.

Abstract

A bulk phantom scalar field (with negative kinetic energy) in a sine--Gordon type potential is used to generate an exact thick brane solution with an increasing warp factor. It is shown that the growing nature of the warp factor allows the localisation of massive as well as massless spin-half fermions on the brane even without any additional non--gravitational interactions. The exact solutions for the localised massive fermionic modes are presented and discussed. The inclusion of a fermion--scalar Yukawa coupling appears to change the mass spectrum and wave functions of the localised fermion though it does not play the crucial role it did in the case of a decreasing warp factor.