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.
9 pages, 1 figure. Version improved considerably: one footnote removed with extended discussion in Sec. I, a new paragraph added at the end of Sec. IV and another new paragraph in Sec. V, one figure and some references added