On new gravitational instantons describing creation of braneworlds

By considering five-dimensional cosmological models with a bulk filled with a pressureless scalar field or equivalently dust matter, and a negative cosmological constant, we have found a regular instantonic solution which is free from any singularity at the origin of the extra coordinate. This instanton describes the five-dimensional asymptotically anti-de Sitter wormhole, when the bulk has a topology R X S-4. Compactified braneworld instantons which are built up from such an instantonic solution describe either a single brane or a string of branes. Their analytical continuation to the pseudo-Riemannian metric can give rise to either four-dimensional inflating branes or solutions with the same dynamical behaviour for extra dimension and branes, in addition to multitemporal solutions. Dust braneworld models with arbitrary dimensions (D greater than or equal to 5) as well as other spatial topologies are also briefly discussed.