Inflating wormholes in the braneworld models
  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.
