On asymmetric brane creation
  We exhaust the brane instanton solutions---an Einstein brane inhabiting at different positions in a 5-dimensional Einstein bulk with negative curvature. We construct a brane instanton model consisting of a brane with asymmetric bulk along two sides of the brane. And the junction condition of the resulting space-time is analyzed in the frame of induced gravity (DGP model). In spirits of quantum gravity of path integral formulism we calculate the Euclidean actions on three canonical paths and then compare the Euclidean actions of different instantons per unit 4-volume. We also compare the Euclidean actions per unit 4-volume of instantons, which consist of a brane gluing to a fixed half, with other Euclidean actions of halves possessing different cosmological constants. 
Hongsheng Zhang, Zongkuan Guo, Chiyi Chen, Xin-Zhou Li
hep-th