Fermion Localization and Resonances on A de Sitter Thick Brane

TL;DR

This paper studies how fermions can be localized and form resonances on a de Sitter thick brane using scalar-fermion couplings, revealing that resonance properties depend on the coupling strength and the power of the scalar field.

Contribution

It introduces a new class of scalar-fermion couplings with odd powers and analyzes the resulting fermionic resonance spectrum on a de Sitter thick brane.

Findings

Massive fermionic resonances are found for both chiralities at large coupling.

Resonance masses and lifetimes are nearly identical for left and right chiral modes.

The number and longevity of resonances increase with the scalar coupling power $k$.

Abstract

In arXiv:0901.3543, the simplest Yukawa coupling $\eta\bar{\Psi}\phi\chi\Psi$ was considered for a two-scalar-generated Bloch brane model. Fermionic resonances for both chiralities were obtained, and their appearance is related to branes with internal structure. Inspired on this result, we investigate the localization and resonance spectrum of fermions on a one-scalar-generated $dS$ thick brane with a class of scalar-fermion couplings $\eta\bar{\Psi}\phi^k\Psi$ with positive odd integer $k$. A set of massive fermionic resonances for both chiralities are obtained when provided large couple constant $\eta$. We find that the masses and life-times of left and right chiral resonances are almost the same, which demonstrates that it is possible to compose massive Dirac fermions from the left and right chiral resonances. The resonance with lower mass has longer life-time. For a same set of parameters, the number of resonances increases with $k$ and the life-time of the lower level resonance for larger $k$ is much longer than the one for smaller $k$.