Lightlike Braneworlds in Anti-de Sitter Bulk Space-times
  We consider five-dimensional Einstein-Maxwell-Kalb-Ramond system self-consistently coupled to a lightlike 3-brane, where the latter acts as material, charge and variable cosmological constant source. We find wormhole-like solutions whose total space-time manifold consists of either (a) two "universes", which are identical copies of the exterior space-time region (beyond the horizon) of 5-dimensional Schwarzschild-anti-de Sitter black hole, or (b) a "right" "universe" comprising the exterior space-time region of Reissner-Nordstroem-anti-de Sitter black hole and a "left" "universe" being the Rindler "wedge" of 5-dimensional flat Minkowski space. The wormhole "throat" connecting these "universes", which is located on their common horizons, is self-consistently occupied by the lightlike 3-brane as a direct result of its dynamics given by an explicit reparametrization-invariant world-volume Lagrangian action. The intrinsic world-volume metric on the 3-brane turns out to be flat, which allows its interpretation as a lightlike braneworld. 
Eduardo Guendelman, Alexander Kaganovich, Emil Nissimov and Svetlana   Pacheva
hep-th gr-qc