Weyl-Invariant Lightlike Branes and Soldering of Black Hole Space-Times
  We consider self-consistent coupling of the recently introduced new class of Weyl-conformally invariant lightlike branes (WILL-branes) to D=4 Einstein-Maxwell system plus a D=4 three-index antisymmetric tensor gauge field. We find static spherically-symmetric solutions where the space-time consists of two regions with different black-hole-type geometries and different values for a dynamically generated cosmological constant, separated by the WILL-brane which ``straddles'' their common event horizon. Furthermore, the WILL-brane produces a potential ``well'' around itself acting as a trap for test particles falling towards the horizon. 
Eduardo Guendelman and Alexander Kaganovich (Ben-Gurion Univ.,   Beer-Sheva), Emil Nissimov and Svetlana Pacheva (Inst. Nucl...