All static and electrically charged solutions with Einstein base manifold in the arbitrary-dimensional Einstein-Maxwell system with a massless scalar field

We present a simple and complete classification of static solutions in the Einstein-Maxwell system with a massless scalar field in arbitrary $n(\ge 3)$ dimensions. We consider spacetimes which correspond to a warped product $M^2 \times K^{n-2}$, where $K^{n-2}$ is a $(n-2)$-dimensional Einstein space. The scalar field is assumed to depend only on the radial coordinate and the electromagnetic field is purely electric. Suitable Ans\"atze enable us to integrate the field equations in a general form and express the solutions in terms of elementary functions. The classification with a non-constant real scalar field consists of nine solutions for $n\ge 4$ and three solutions for $n=3$. A complete geometric analysis of the solutions is presented and the global mass and electric charge are determined for asymptotically flat configurations. There are two remarkable features for the solutions with $n\ge 4$: (i) Unlike the case with a vanishing electromagnetic field or constant scalar field, asymptotically flat solution is not unique, and (ii) The solutions can asymptotically approach the Bertotti-Robinson spacetime depending on the integrations constants. In accordance with the no-hair theorem, none of the solutions are endowed of a Killing horizon.Comment: 38 pages, 1 figure, 1 table. Some typos fixed. References adde

Gauss-Bonnet braneworld redux: A novel scenario for the bouncing universe

We propose a new scenario for the bouncing universe in a simple five-dimensional braneworld model in the framework of Einstein-Gauss-Bonnet gravity, which works even with ordinary matter on the brane. In this scenario, the so-called branch singularity located at a finite physical radius in the bulk spacetime plays an essential role. We show that a three-brane moving in the bulk may reach and pass through it in spite of the fact that it is a curvature singularity. The bulk spacetime is extended beyond the branch singularity in the C^0 sense and then the branch singularity is identified as a massive thin shell. From the bulk point of view, this process is the collision of the three-brane with the shell of branch singularity. From the point of view on the brane, this process is a sudden transition from the collapsing phase to the expanding phase of the universe. The present result opens a completely new possibility to achieve the bouncing brane universe as a higher-curvature effect.Comment: 34 pages, 3 figures, 2 tables; v2, sections rearranged, typos corrected; v3, final version to appear in Physical Review

Hamiltonian dynamics of Lovelock black holes with spherical symmetry

We consider spherically symmetric black holes in generic Lovelock gravity. Using geometrodynamical variables we do a complete Hamiltonian analysis, including derivation of the super-Hamiltonian and super-momentum constraints and verification of suitable boundary conditions for asymptotically flat black holes. Our analysis leads to a remarkably simple fully reduced Hamiltonian for the vacuum gravitational sector that provides the starting point for the quantization of Lovelock block holes. Finally, we derive the completely reduced equations of motion for the collapse of a spherically symmetric charged, self-gravitating complex scalar field in generalized flat slice (Painlev\'{e}-Gullstrand) coordinates.Comment: 53 pages, including two major appendices; some typos fixed; version published in CQ