Inflating wormholes in the braneworld models

TL;DR

This paper explores how wormholes in braneworld models evolve during inflation, showing that some can grow or transform into black holes, with implications for understanding higher-dimensional gravity and cosmology.

Contribution

It investigates the evolution of inflating wormholes in braneworld scenarios, including embedding conditions, dynamics during inflation, and the potential transformation into black holes.

Findings

Wormholes can be supported by nonlocal brane effects without violating energy conditions.

During inflation, some wormholes decay, while others may become black holes.

A zero redshift wormhole solution was explicitly obtained.

Abstract

The braneworld model, in which our Universe is a three-brane embedded in a five-dimensional bulk, allows the existence of wormholes, without any violation of the energy conditions. A fundamental ingredient of traversable wormholes is the violation of the null energy condition (NEC). However, in the brane world models, the stress energy tensor confined on the brane, threading the wormhole, satisfies the NEC. In conventional general relativity, wormholes existing before inflation can be significantly enlarged by the expanding spacetime. We investigate the evolution of an inflating wormhole in the brane world scenario, in which the wormhole is supported by the nonlocal brane world effects. As a first step in our study we consider the possibility of embedding a four-dimensional brane world wormhole into a five dimensional bulk. The conditions for the embedding are obtained by studying the junction conditions for the wormhole geometry, as well as the full set of the five dimensional bulk field equations. For the description of the inflation we adopt the chaotic inflation model. We study the dynamics of the brane world wormholes during the exponential inflation stage, and in the stage of the oscillating scalar field. A particular exact solution corresponding to a zero redshift wormhole is also obtained. The resulting evolution shows that while the physical and geometrical parameters of a zero redshift wormhole decay naturally, a wormhole satisfying some very general initial conditions could turn into a black hole, and exist forever.