Fermionic and Bosonic Stabilizing Effects for Type I and Type II Dimension Bubbles

TL;DR

This paper investigates the stabilization mechanisms of dimension bubbles, a type of 4d soliton from 5d theories with extra dimensions, highlighting how particle entrapment and photon effects contribute to their stability.

Contribution

It introduces a detailed analysis of fermionic, bosonic, and photon effects in stabilizing dimension bubbles, expanding understanding of their properties and potential long-lived states.

Findings

Type I bubbles can be stabilized by particle entrapment.

Type II bubbles expel massive particles but can be stabilized by photons.

Plasma-filled bubbles may exist as long-lived metastable states.

Abstract

We consider two types of "dimension bubbles", which are viewed as 4d nontopological solitons that emerge from a 5d theory with a compact extra dimension. The size of the extra dimension varies rapidly within the domain wall of the soliton. We consider the cases of type I (II) bubbles where the size of the extra dimension inside the bubble is much larger (smaller) than outside. Type I bubbles with thin domain walls can be stabilized by the entrapment of various particle modes whose masses become much smaller inside than outside the bubble. This is demonstrated here for the cases of scalar bosons, fermions, and massive vector bosons, including both Kaluza-Klein zero modes and Kaluza-Klein excitation modes. Type II bubbles expel massive particle modes but both types can be stabilized by photons. Plasma filled bubbles containing a variety of massless or nearly massless radiation modes may exist as long-lived metastable states. Furthermore, in contrast to the case with a "gravitational bag", the metric for a fluid-filled dimension bubble does not exhibit a naked singularity at the bubble's center.