Fermionic spectral walls in kink collisions

TL;DR

This paper demonstrates the existence of spectral walls in fermion-coupled bosonic models, showing how they affect kink dynamics and lead to separation of kink-fermion bound states.

Contribution

It introduces the concept of fermionic spectral walls, extending the spectral wall phenomenon to models with fermions coupled to bosonic solitons.

Findings

Spectral walls occur after coupling bosonic models to fermions.

Kink-fermion bound states can be separated at spectral walls.

Fermionic clouds spread in the region before the spectral wall.

Abstract

We show that a spectral wall, i.e., an obstacle in the dynamics of a bosonic soliton, which arises due to the transition of a normal mode into the continuum spectrum, exists after coupling the original bosonic model to fermions. This spectral wall can be experienced if the boson or fermion field is in an excited state. Furthermore, while passing through a spectral wall, an incoming kink-fermion bound state can be separated into purely bosonic kink, which continues to move to spatial infinity and a fermionic cloud that spreads in the region before the wall.