Branes on Charged Dilatonic Backgrounds: Self-Tuning, Lorentz Violations and Cosmology

We study the motion of an n-brane in an n + q + 2 dimensional background that has dilatonic q-brane singularities and that is charged under an antisymmetric tensor field. The background spacetime is maximally symmetric in the n-dimensions parallel to the n-brane with constant curvature k = 0,±1. For k = 1 the bulk solutions correspond to black q-branes. For k = 0,−1 the geometry resembles the ‘white hole’ region of the Reissner–Nördstrom solution with a past Cauchy horizon. The metric between the (timelike) singularity and the horizon is static whereas beyond the horizon it is cosmological. For codimension one n-brane, these charged dilatonic backgrounds interpolate between the original scalar self-tuning and the black hole geometry and thus provide a way to avoid the naked singularity problem and/or the need of having exotic matter on the brane. These backgrounds are asymmetrically warped and so break 4D Lorentz symmetry in a way that is safe for particle physics but may lead to faster than light propagation in the gravitational sector.