Cargèse Lectures on Brane Induced Gravity

Gabadadze, Gregory

doi:10.1016/j.nuclphysbps.2007.06.005

Cited by 36 publications

(31 citation statements)

References 49 publications

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“…[3][4] in the DGP model. This enabled us to run fully nonlinear N -body simulations of this model and compare to simulations where the field equations are linearized, where standard gravity is used only for perturbations (but not for the background), and to fully standard gravity simulations.…”

Section: Discussionmentioning

confidence: 99%

Large-scale structure in brane-induced gravity. II. Numerical simulations

Chan

Scoccimarro

2009

Phys. Rev. D

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We use N -body simulations to study the nonlinear structure formation in brane-induced gravity, developing a new method that requires alternate use of Fast Fourier Transforms and relaxation. This enables us to compute the nonlinear matter power spectrum and bispectrum, the halo mass function, and the halo bias. From the simulation results, we confirm the expectations based on analytic arguments that the Vainshtein mechanism does operate as anticipated, with the density power spectrum approaching that of standard gravity within a modified background evolution in the nonlinear regime. The transition is very broad and there is no well defined Vainshtein scale, but roughly this corresponds to k * ≃ 2 h Mpc −1 at redshift z = 1 and k * ≃ 1 h Mpc −1 at z = 0. We checked that while extrinsic curvature fluctuations go nonlinear, and the dynamics of the branebending mode C receives important nonlinear corrections, this mode does get suppressed compared to density perturbations, effectively decoupling from the standard gravity sector. At the same time, there is no violation of the weak field limit for metric perturbations associated with C. We find good agreement between our measurements and the predictions for the nonlinear power spectrum presented in paper I, that rely on a renormalization of the linear spectrum due to nonlinearities in the modified gravity sector. A similar prediction for the mass function shows the right trends. Our simulations also confirm the induced change in the bispectrum configuration dependence predicted in paper I.

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Section: Discussionmentioning

confidence: 99%

Large-scale structure in brane-induced gravity. II. Numerical simulations

Chan

Scoccimarro

2009

Phys. Rev. D

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“…For other related works, e.g., [2 -16]. For a recent review of massive gravity in the context of infinite volume extra dimensions, see, e.g., [17] and references therein. For a recent review of spontaneous breaking of diffeomorphism symmetry in the context of the Lorentz-violating ChernSimons modification of gravity, see [18] and references therein.…”

Section: Introductionmentioning

confidence: 99%

Massive gravity in Minkowski space via the gravitational Higgs mechanism

Kakushadze¹

2008

Phys. Rev. D

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In the gravitational Higgs mechanism graviton components acquire mass in the process of spontaneous breaking of diffeomorphisms (via scalar vacuum expectation values). Recently, the gravitational Higgs mechanism was discussed in the context of obtaining massive gravity directly in four dimensions. We discuss a setup, with all diffeomorphisms spontaneously broken by scalars, where the gravitational Higgs mechanism results in massive gravity in Minkowski space with no nonunitary propagating modes. This is achieved by including higher derivative terms in the scalar sector. Decoupling the nonunitary mode (trace of the graviton) then requires tuning a single parameter, namely, the cosmological constant. We also discuss a setup where only spatial diffeomorphisms are broken. In this case we obtain massive gravity in Minkowski space with only transverse modes propagating, so the mode count is the same as for a massless graviton.

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“…There is some indication that the SA branch is pathological at the nonperturbative level [13], coming from the known exact solutions for domain walls [14] and pointlike sources [15] localized on the brane (although the bulk solution is not known in the latter case). In both cases, the effective gravitational mass (or tension) of the source is negative from the five dimensional point of view, which might signal an instability in the full nonlinear theory.…”

Section: Introductionmentioning

confidence: 99%

Bubbles in the self-accelerating universe

et al. 2007

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We revisit the issue of the stability in the Dvali-Gabadadze-Porrati model by considering the nucleation of bubbles of the conventional branch within the self-accelerating branch. We construct an instanton describing this process in the thin wall approximation. On one side of the bubble wall, the bulk consists of the exterior of the brane, while on the other side it is the interior. The solution requires the presence of a 2-brane (the bubble wall) which induces the transition. However, we show that this instanton cannot be realized as the thin wall limit of any smooth solution. Once the bubble thickness is resolved, the equations of motion do not allow O4 symmetric solutions joining the two branches. We conclude that the thin wall instanton is unphysical, and that one cannot have processes connecting the two branches, unless negative tension bubble walls are introduced. This also suggests that the self-accelerating branch does not decay into the conventional branch nucleating bubbles. We comment on other kinds of bubbles that could interpolate between the two branches.

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Cargèse Lectures on Brane Induced Gravity

Cited by 36 publications

References 49 publications

Large-scale structure in brane-induced gravity. II. Numerical simulations

Large-scale structure in brane-induced gravity. II. Numerical simulations

Massive gravity in Minkowski space via the gravitational Higgs mechanism

Bubbles in the self-accelerating universe

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