Variable-tension lightlike brane as a gravitational source of traversable Misner-Wheeler-type wormholes

Consistent Lagrangian description of variable-tension lightlike p-branes (LL-branes) is presented in two equivalent forms - a Polyakov-type formulation and a dual to it Nambu-Goto-type formulation. An important and non-standard characteristic feature of the LL-branes is that the brane tension appears as a non-trivial additional dynamical degree of freedom. We consider properties of p=2LL-brane dynamics (as a test brane) in D=4 Kerr or Kerr-Newman gravitational backgrounds in some detail. It is shown that the LL-brane automatically positions itself on the horizon and rotates along with the same angular velocity. Finally, we construct explicitly a traversable wormhole of Misner-Wheeler type based on a Reissner-Nordstroem geometry. This wormhole is constructed as a self-consistent solution of the electrically sourceless Einstein-Maxwell system in the D=4 bulk interacting with a LL-brane. The pertinent wormhole throat is located precisely at the LL-brane sitting on the outer Reissner-Nordstroem horizon with the Reissner-Nordstroem mass and charge being functions of the dynamical LL-brane tension