Branes on charged dilatonic backgrounds: self-tuning, Lorentz violations and cosmology

We construct an n+q+2 dimensional background that has dilatonic q-branesingularities and that is charged under an antisymmetric tensor field, thebackground spacetime being maximally symmetric in n-dimensions with constantcurvature k=0,+1,-1. For k=1 the bulk solutions correspond to black q-branes.For k=0,-1 the geometry resembles the `white hole' region of theReissner-N"ordstrom solution with a past Cauchy horizon. The metric between the(timelike) singularity and the horizon is static whereas beyond the horizon itis cosmological. In the particular case of q=0, we study the motion of acodimension one n-brane in these charged dilatonic backgrounds that interpolatebetween the original scalar self-tuning and the black hole geometry and providea way to avoid the naked singularity problem and/or the need of having exoticmatter on the brane. These backgrounds are asymmetrically warped and so break4D Lorentz symmetry in a way that is safe for particle physics but may lead tofaster than light propagation in the gravitational sector.Comment: 28 pages, 4 figures, JHEP LaTeX. Few typos corrected. Published versio