A short review of "DGP Specteroscopy"

TL;DR

This paper reviews the main findings of hep-th/0604086, highlighting the presence of a ghost in the spectrum of linearized vacuum perturbations in the DGP model's self-accelerating branch, and discusses counterarguments from hep-th/0607099.

Contribution

It provides a concise review of the spectral properties of perturbations in the DGP model and clarifies the ghost issue in the self-accelerating branch.

Findings

Ghost present in the spectrum for all brane tensions

Perturbations analyzed in the self-accelerating branch

Discussion of counterarguments from other studies

Abstract

In this paper we provide a short review of the main results developed in hep-th/0604086. We focus on linearised vacuum perturbations about the self-accelerating branch of solutions in the DGP model. These are shown to contain a ghost in the spectrum for any value of the brane tension. We also comment on hep-th/0607099, where some counter arguments have been presented.