Ghosts in the self-accelerating DGP branch with Gauss-Bonnet effect
  The Dvali-Gabadadze-Porrati brane-world model provides a possible approach to
address the late-time cosmic acceleration. However, it has subsequently been
pointed out that a ghost instability will arise on the self-accelerating
branch. Here, we carefully investigate whether this ghost problem could be
possibly cured by introducing the Gauss-Bonnet term in the five-dimensional
bulk action, a natural generalization to the Dvali-Gabadadze-Porrati model. Our
analysis is carried out for a background where a de Sitter brane is embedded in
an anti-de Sitter bulk. Our result shows that the ghost excitations cannot be
avoided even in this modified model.
