The fermion spectrum in braneworld collisions

TL;DR

This paper investigates how fermions initially localized on one brane in a braneworld scenario transfer during brane collisions, analyzing the resulting fermion spectra and their dependence on collision velocity and coupling.

Contribution

It extends previous work by numerically computing the fermion mode spectrum during brane collisions, revealing dependence on velocity and coupling, and characterizing mode delocalization.

Findings

Fermion spectra are highly sensitive to collision velocity.

High-momentum fermion modes tend to delocalize and radiate.

Fermion-scalar coupling significantly influences mode transfer.

Abstract

In braneworld collisions fermions originally localised on one brane can be transferred to another brane, or to a space-time boundary. By modelling branes as scalar field kinks we bounce them off boundaries and study resulting effects according to a braneworld observer. Extending on our previous work, we numerically compute the spectrum of excitations of fermion modes localised on the brane and boundary, in terms of the momentum $k$ along the brane dimensions. We find that the spectrum depends strongly on collision velocity and fermion-scalar coupling. Also, high-momentum modes tend to ``fall off'' the kinks and become delocalised radiation.