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Title: More on ghosts in the Dvali-Gabadaze-Porrati model

Abstract

It is shown by an explicit calculation that the excitations about the self-accelerating cosmological solution of the Dvali-Gabadaze-Porrati model contain a ghost mode. This raises serious doubts about viability of this solution. Our analysis reveals the similarity between the quadratic theory for the perturbations around the self-accelerating universe and an Abelian gauge model with two Stueckelberg fields.

Authors:
;  [1];  [2]
  1. Institute for Nuclear Research of the Russian Academy of Sciences, 60th October Anniversary prospect 7a, Moscow 117312 (Russian Federation)
  2. Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 2EG (United Kingdom)
Publication Date:
OSTI Identifier:
20776754
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 73; Journal Issue: 4; Other Information: DOI: 10.1103/PhysRevD.73.044016; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; COSMOLOGY; DISTURBANCES; EXCITATION; MATHEMATICAL MODELS; MATHEMATICAL SOLUTIONS; UNIVERSE

Citation Formats

Gorbunov, Dmitry, Sibiryakov, Sergei, and Koyama, Kazuya. More on ghosts in the Dvali-Gabadaze-Porrati model. United States: N. p., 2006. Web. doi:10.1103/PhysRevD.73.044016.
Gorbunov, Dmitry, Sibiryakov, Sergei, & Koyama, Kazuya. More on ghosts in the Dvali-Gabadaze-Porrati model. United States. doi:10.1103/PhysRevD.73.044016.
Gorbunov, Dmitry, Sibiryakov, Sergei, and Koyama, Kazuya. Wed . "More on ghosts in the Dvali-Gabadaze-Porrati model". United States. doi:10.1103/PhysRevD.73.044016.
@article{osti_20776754,
title = {More on ghosts in the Dvali-Gabadaze-Porrati model},
author = {Gorbunov, Dmitry and Sibiryakov, Sergei and Koyama, Kazuya},
abstractNote = {It is shown by an explicit calculation that the excitations about the self-accelerating cosmological solution of the Dvali-Gabadaze-Porrati model contain a ghost mode. This raises serious doubts about viability of this solution. Our analysis reveals the similarity between the quadratic theory for the perturbations around the self-accelerating universe and an Abelian gauge model with two Stueckelberg fields.},
doi = {10.1103/PhysRevD.73.044016},
journal = {Physical Review. D, Particles Fields},
number = 4,
volume = 73,
place = {United States},
year = {Wed Feb 15 00:00:00 EST 2006},
month = {Wed Feb 15 00:00:00 EST 2006}
}
  • We present here the general transformation that leaves unchanged the form of the field equations for perfect fluid cosmologies in the Dvali-Gabadadze-Porrati (DGP) brane-world model. Specifically, a prescription for relating exact solutions with different equations of state is provided, and the symmetries found can be used as algorithms for generating new cosmological models from previously known ones. We also present, implicitly, the first known exact DGP perfect fluid spacetime. A particular case of the general transformation is used to illustrate the crucial role played both by the number of scalar fields and the extra-dimensional effects in the occurrence of inflation.more » In particular, we see that assisted inflation does not proceed at all times for one of the two possible ways in which the brane can be embedded into the bulk.« less
  • The Dvali-Gabadadze-Porrati (DGP) model with additional terms in the action is considered. These terms have a special form and include auxiliary scalar fields without kinetic terms, which are nonminimally coupled to gravity. The use of these fields allows one to exclude the mode, which corresponds to the strong coupling effect, from the theory. Effective four-dimensional theory on the brane appears to be the same, as in the original DGP model.
  • The self-accelerating braneworld model (DGP) can be tested from measurements of the expansion history of the Universe and the formation of structure. Current constraints on the expansion history from supernova luminosity distances, the cosmic microwave background (CMB), and the Hubble constant exclude the simplest flat DGP model at about 3{sigma}. Even including spatial curvature, the best-fit open DGP model is a marginally poorer fit to the data than flat {lambda}CDM. Moreover, its substantially different expansion history raises serious challenges for the model from structure formation. A dark energy model with the same expansion history would predict a highly significant discrepancymore » with the baryon oscillation measurement due the high Hubble constant required. For the DGP model to satisfy this constraint new nonlinear phenomena must correct this discrepancy. Likewise the large enhancement of CMB anisotropies at the lowest multipoles due to the ISW effect would require either a cutoff in the initial power or new phenomena at the cross-over scale. A prediction that is robust to both possibilities is that high-redshift galaxies should be substantially correlated with the CMB through the ISW effect. This correlation should provide a sharp test of the DGP model in the future.« less
  • We investigate the effect of the bulk contents in the Dvali-Gabadadze-Porrati (DGP) braneworld on the evolution of the universe. We find that, although the pure DGP model cannot accommodate the transition of the effective equation of state of dark energy, once the bulk matter T{sub 5}{sup 5} is considered, the modified model can realize the w{sub eff} crossing -1. However, this transition of the equation of state cannot be realized by just considering bulk-brane energy exchange or the Gauss-Bonnet effect while the bulk matter contribution is not included. T{sub 5}{sup 5} plays the major role in the modified DGP modelmore » to have the w{sub eff} crossing -1 behavior. We show that our model can describe the superacceleration of our universe with the equation of state of the effective dark energy and the Hubble parameter in agreement with observations.« less
  • We present a generalization of the Dvali-Gabadadze-Porrati scenario to higher codimensions which, unlike previous attempts, is free of ghost instabilities. The 4D propagator is made regular by embedding our visible 3-brane within a 4-brane, each with their own induced gravity terms, in a flat 6D bulk. The model is ghost-free if the tension on the 3-brane is larger than a certain critical value, while the induced metric remains flat. The gravitational force law ''cascades'' from a 6D behavior at the largest distances followed by a 5D and finally a 4D regime at the shortest scales.