Predictive Power of Strong Coupling in Theories with Large Distance Modified Gravity

Gia Dvali

REVIEW

Predictive Power of Strong Coupling in Theories with Large Distance Modified Gravity

Gia Dvali

High Energy Physics - Theory · Submitted 1 Oct 2006 · 23 references

Pith's verdict: The necessity argument and the α-generalization of the Vainshtein scale are solid; the headline correction (1.4) is an extrapolation whose exponent is asserted rather than derived.

T0 · AI review

How this review was made: An AI referee (selfhosted/deepseek-v4.1-flash) read the paper on November 11, 2026 and answered a fixed list of questions about it. T0 is the starting level every paper gets. The levels describe how deeply Pith has checked the paper, never the authors.

T0 AI review An AI read the paper and answered a fixed list of questions.
T1 Audit Automatic checks that the references and files the paper relies on exist and match.
T2 Compute The paper's code or calculations re-run with the same results.
T3 Formal statement The claims written out in a formal math language a computer can read.
T4 Proof Those claims proved, and the proof checked by computer.

How Pith checks papers →

· 3 major objections · 7 minor · Ask about this paper · The compiled record · Read the full review →

Challenge this review Comment (0) Read on arXiv ↗

Cite ▾

arXiv IDhep-th/0610013 (version 1)

Pith IDBR2J6B2I, Pith's permanent record of this paper and its review

CitationGia Dvali. "Predictive Power of Strong Coupling in Theories with Large Distance Modified Gravity." arXiv:hep-th/0610013 (2006). https://pith.science/paper/BR2J6B2I

Cite this reviewBibTeX for Pith's review of this paper

Claim paper

Why Pith says this

Highlight any text to comment on it.

Editor's note

read the letter

Short version: the necessity argument holds up and the generalization is real; the headline formula is an extrapolation presented a bit more firmly than the derivation supports. What holds up: Section 2's unitarity bound (α ≥ 0 from a non-negative spectral density) is clean and standard. More importantly, the chain from 'ghost-free Pauli-Fierz structure ⇒ five polarizations ⇒ vDVZ ⇒ must be strongly coupled or already excluded by solar-system data' is a genuine effective-field-theory argument, and it is the paper's real contribution. Generalizing the Vainshtein scale to r* = (r_c^{4(1-α)} r_g)^{1/(1+4(1-α))} for arbitrary α is new relative to the α = 0 and α = 1/2 literature, and the α = 1/2 check against [16,18] is real support. Where it is soft: the exponent in (4.7), 3/2 − 2α. The paper says it is 'fixed from the two requirements' — matching χ ~ r_g/r* at r = r* and analyticity inside r* in r_c^{2(α-1)}. A normalization and an analyticity class do not determine a power. The exponent comes from the nonlinear equation of motion for χ inside r*, which depends on the trilinear vertex (4.5), which the paper obtains by 'straightforward power counting' extrapolated from the two known cases. For α = 1/2 the answer is checked; for general α it is not. The paper is honest about this — it says completions for general α 'have not been studied' and flags the analyticity assumption — but the sentence 'knowing the explicit form of this completion is unnecessary' is too strong. It is necessary for the exponent. Two smaller things. The paper concedes (1.4) was 'already suggested' in [10,11], so the novelty is the α-generalization, not the formula. And the Note Added's dismissal of the perturbative ghost claims [22] rests on the same r*-argument, so it is a consistency statement, not independent evidence. None of this sinks the paper. The qualitative claim is right and the prediction is falsifiable by lunar ranging. But the quantitative part is a one-parameter family of extrapolations, and it should be read that way. Who should read it: anyone working on Vainshtein/strong-coupling in modified gravity, and experimentalists who want the scaling to test against. It is a standard reference for the general-α formula. Recommendation: send it out. The unitarity argument and the r* generalization are worth referee time, and the exponent question is exactly the kind of thing a referee should press on.

Referee report

Significance

The paper's organizing idea is valuable and, if correct, consequential: it converts an entire class of infrared modifications of gravity into a target for precision gravitational tests at scales far below the cosmological horizon, rather than only for cosmology. The general one-parameter parametrization of Eq. (1.3), the identification of r* as a source-dependent strong-coupling scale that plays the role of a second horizon for the longitudinal mode, and the explicit falsifiable prediction of Eq. (4.8) are all genuine contributions, and the paper is commendably clear that the strong-coupling phenomenon is what saves such theories from the vDVZ discontinuity rather than an embarrassment to be cured. The check of Eq. (1.4) against the known α = 1/2 solutions of [16] and [18] is real support, and the unitarity argument of Section 2 is clean within its stated assumptions. The value of the paper, however, rests on the quantitative formula (1.4) holding for general α, and that is where the manuscript is thinnest.

Major objections (3)

[§4, Eqs. (4.6)-(4.7) and Eq. (1.4)] The exponent 3/2 - 2α in Eq. (4.7) is the load-bearing input for the paper's headline prediction, Eq. (1.4), and it is not derived from the two requirements the text invokes. A normalization condition (χ ~ r_g/r* at r = r*) fixes only the coefficient, and the analyticity requirement (approximability by a series in r_c^{2(α-1)}) fixes only the admissible class of functions; neither determines a power. Indeed 3/2 - 2α is not of the form 2n(1-α) for any n, so the stated analyticity requirement does not by itself produce it. The exponent must come from the nonlinear equation of motion for χ inside r*, which is never written, and whose structure depends on the completion that the paper explicitly says has not been studied for general α. As written, the exponent is fixed by matching the two known cases, α = 0 (Vainshtein, exponent 3/2) and α = 1/2 (DGP, exponent 1/2), and interpolating linearly in α. That is a reasonable conjecture, but it should be presented as one. I would ask the author either to write the nonlinear equation and derive the exponent, or to state plainly that Eq. (4.7) is an interpolation calibrated at the two known values. In the same vein, the sentence in §4 that 'knowing the explicit form of this completion is unnecessary' is too strong: the prediction depends on the completion's trilinear vertex and on the exponent of the solution inside r*.
[§4, Eq. (4.5)] The trilinear vertex (r_c k)^{4(1-α)}k² is obtained by 'straightforward power counting' and is checked only at α = 0 and α = 1/2. Since r* in Eq. (4.6) follows directly from this vertex, the source-dependent strong-coupling scale — arguably the paper's most robust qualitative statement after the existence of strong coupling itself — inherits the assumption. It would strengthen the paper considerably to show the power counting explicitly: which terms of the Stückelberg expansion contribute at leading order in 1/r_c, and why no other cubic vertex carries a stronger singularity in r_c. A different leading vertex would change the exponent in Eq. (4.6) and hence the source-dependence that the abstract advertises.
[Note Added] The paragraph dismissing the ghost analyses of [22] rests on the observation that on the self-accelerated background □χ ~ H_0²/M_P and on the fact that r* ~ H_0^{-1} for the Universe, so that perturbation theory is claimed to be invalid. The observation is suggestive, but the conclusion that the published instability results are artifacts of an invalid expansion is asserted rather than demonstrated; no nonperturbative computation or alternative expansion scheme is given. Because the paper's framing — that strong coupling is the only cure that saves such theories — depends on the theory not being excluded on other grounds, this paragraph carries more weight than its length suggests. I would ask either for a concrete nonperturbative argument, or for the claim to be softened to the defensible statement that the perturbative analyses do not apply in this regime.

Minor objections (7)

[§1 and §2] The phrase 'the unitarity range 0 ⩽ α ⩽ 1' in §1 is not supported by §2, which establishes only α ≥ 0. The upper end comes from Eq. (1.3), that is, from requiring m²(□) to dominate over the Einstein term at large r, not from unitarity. Please relabel the bound accordingly.
[Eq. (4.3)] The normalization of χ should be stated. The term r_c^{2(1-α)}∂_μ∂_ν/(3□^α)χ does not appear to carry the same mass dimension as (1/6)η_{μν}χ for general α, so the reader cannot check the matching to Eq. (4.4) without the convention for χ.
[§4] The statement that 'existing Lunar Ranging constraints already rule out theories with α significantly above 1/2' should be quantified: which dataset, and what bound on α does it imply?
[§2, Eq. (2.4)] The argument that α < 0 would force Δ(0) = 0 assumes that the Källén-Lehmann form (2.3) with positive spectral density applies to the full theory, which is strongly coupled at the scales of interest. A sentence acknowledging this assumption would be appropriate.
[§1] The assertion that 'there exists an unique class of ghost-free linearized theories of a spin-2 field with the above properties' should carry a citation to the uniqueness result for the Pauli-Fierz-type linearized structure, since the abstract's 'all ghost-free theories' claim rests on it.
[Reference [11]] Reference [11] includes an unpublished item (Dvali, Nunez and Solganik). Since §1 credits [10,11] with having already suggested Eq. (1.4), the priority claim rests partly on unpublished work; please make the published/unpublished status explicit.
[Throughout] Typographical corrections: 'Palui-Fierz' in §3, 'lineareazed', 'Eisteinian', and 'the hole of a second horizon' in §5, and 'tachions' in §1.

How Pith checks papers → · Full audit of this paper →

The paper

The paper claims

Any theory that bends gravity at cosmic distances must be strongly coupled, or the solar system has already ruled it out.

The reading

Dvali asks what *any* theory that weakens gravity at cosmological distances must look like, and answers that it cannot be a weakly coupled one. A ghost-free graviton that goes massive at long range necessarily carries extra polarizations, and if those stayed weakly coupled down to solar-system scales the linearized metric would have the wrong tensorial structure — the van Dam–Veltman–Zakharov discontinuity — and existing gravitational data would already exclude the theory. The escape is strong coupling: the scalar polarization's self-interactions grow until, at a source-dependent radius $r_*$, the linear approximation breaks down and the disagreement with observation is washed out. What makes this predictive rather than a loophole is that the same mechanism fixes the size of the surviving correction to Newtonian gravity, so the whole class of theories becomes testable at scales far below the cosmic horizon.

What carries the argument

The load-bearing object is the source-dependent scale $r_*$, a second horizon that governs the extra scalar polarization the way $r_g$ governs the ordinary tensor modes. It is fixed by matching the strong-coupling vertex $(r_c k)^{4(1-α)}k^2$ against the linear solution, and it is what converts a would-be refutation into a prediction: outside $r_*$ the linear metric is correct and carries the vDVZ discontinuity, inside $r_*$ the non-linear scalar field screens it, and the two regimes must join at $r_*$. The joining conditions — that $χ$ reach $r_g/r_*$ at $r = r_*$, and that the interior be expandable analytically in $r_c^{2(α-1)}$ — are what fix the exponent $3/2 - 2α$ in the correction.

Extended reading notes

Core claim

The paper claims that large-distance modifications of gravity form a one-parameter family, labelled by $m^2(□) ≃ r_c^{2(α-1)}□^{α}$ with $0 ≤ α ≤ 1$, where $r_c$ is the crossover scale at which Newtonian dynamics changes. Unitarity of the propagator's spectral representation forbids $α < 0$, so the massive Pauli–Fierz graviton ($α = 0$) is the lower end and the five-dimensional brane-world model ($α = 1/2$) is the only case with a known ghost-free covariant completion. Every member of this family must be strongly coupled: the trilinear self-interaction of the longitudinal graviton scales as $(r_c k)^{4(1-α)}k^2$, and it overtakes the linear term at a radius $r_* = (r_c^{4(1-α)} r_g)^{1/(1+4(1-α))}$ that depends on the source mass through $r_g = 2G_N M$. Inside $r_*$ the linear metric is invalid, which is what saves the theory from the solar-system bounds. The residual correction to the potential for $r ≪ r_*$ is $δ ∼ (r/r_c)^{2(1-α)}$√$(r/r_g)$, and for $r_c$ of order the Hubble radius this gives an anomalous perihelion advance per orbit of order $(r H_0)^{2(1-α)}$√$(r/r_g)$ — small enough to have escaped detection so far, but large enough to be probed by improved ranging.

Load-bearing premise

The functional form of the correction is not derived from a completion: it is fixed by assuming that inside $r_*$ the solution can be expanded analytically in powers of $r_c^{2(α-1)}$, and the paper concedes that non-linear completions for general $α$ have not been studied.

Editorial extensions

If this is right

Every ghost-free large-distance modification of gravity is strongly coupled at solar-system scales, so no such theory can be a weakly coupled effective field theory all the way down.
The correction to the gravitational potential scales as $(r/r_c)^{2(1-α)}$√$(r/r_g)$, making lighter sources deviate from Einsteinian gravity at shorter distances — a universal, source-dependent signature.
For $r_c = H_0^{-1}$, the anomalous perihelion advance per orbit is of order $(rH_0)^{2(1-α)}$√$(r/r_g)$, which existing lunar ranging already constrains for $α$ appreciably above $1/2$.
The only gravitating source in the observable Universe that sits at its own $r_*$ is the Universe itself, which explains why cosmological expansion can be strongly modified while solar-system gravity looks normal.
Perturbative stability analyses of the self-accelerated background are invalid, because the background sits at $r_* ∼ H_0^{-1}$ where the expansion in $G_N$ breaks down.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

If the picture is right, the same screening logic should apply to any light scalar coupled to matter — the correction's dependence on $r_g$ is a template for how a screening scale trades against source mass, and precision tests at different source masses could separate the $α$ dependence from the screening form.
The paper's own logic implies a sharp prediction for compact sources: for a sufficiently dense object $r_*$ can approach $r_g$, and the intermediate regime where neither the linear nor the fully screened approximation holds becomes observable — a regime no current experiment targets.
Because $α$ is continuous and the correction grows with $α$, precision gravitational tests become a probe of the deep structure of the completion rather than of cosmology; a measured $α$ would point at the dimensionality of the underlying extra space.
The stability argument in the Note Added cuts both ways: if non-perturbative effects at $r_*$ can stabilize the self-accelerated background, they may also produce observable non-linear structure at galactic scales, which is a separate and currently unaddressed test.

Original abstract

We consider theories that modify gravity at cosmological distances, and show that any such theory must exhibit a strong coupling phenomenon, or else it is either inconsistent or is already ruled out by the solar system observations. We show that all the ghost-free theories that modify dynamics of spin-2 graviton on asymptotically flat backgrounds, automatically have this property. Due to the strong coupling effect, modification of the gravitational force is source-dependent, and for lighter sources sets in at shorter distances. This universal feature makes modified gravity theories predictive and potentially testable not only by cosmological observations, but also by precision gravitational measurements at scales much shorter than the current cosmological horizon. We give a simple parametrization of consistent large distance modified gravity theories and their predicted deviations from the Einsteinian metric near the gravitating sources.

The compiled record

The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.

Compiled by classifier-1.13-20260917 via OpenRouter, question bank abstract-p1-20260923, 2026-09-23: 1 request, 4,318 input tokens, $0.0002 reported.

What the abstract itself states, as probabilities: claims first 0.04 · states limitation 0.16 · human participants 0.01 · controlled comparison 0.08 · randomized assignment 0.01 · states quantitative result 0.06 · compares with prior results 0.18 · mentions code or data availability 0.01.

The abstract, sentence by sentence

arXiv listing abstract v1. Results and the main claim are underlined; show every role.

We consider theories that modify gravity at cosmological distances, and show that any such theory must exhibit a strong coupling phenomenon, or else it is either inconsistent or is already ruled out by the solar system observations. We show that all the ghost-free theories that modify dynamics of spin-2 graviton on asymptotically flat backgrounds, automatically have this property. Due to the strong coupling effect, modification of the gravitational force is source-dependent, and for lighter sources sets in at shorter distances. This universal feature makes modified gravity theories predictive and potentially testable not only by cosmological observations, but also by precision gravitational measurements at scales much shorter than the current cosmological horizon. We give a simple parametrization of consistent large distance modified gravity theories and their predicted deviations from the Einsteinian metric near the gravitating sources.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#	sentence	role	the authors' own work	states the main conclusion	strength
s0	We consider theories that modify gravity at cosmological distances, and show that any such theory must exhibit a strong coupling phenomenon, or else it is either inconsistent or is already ruled out by the solar system observations.	result 0.84	0.89	0.87	asserted 1.00
s1	We show that all the ghost-free theories that modify dynamics of spin-2 graviton on asymptotically flat backgrounds, automatically have this property.	result 0.92	0.90	0.12	asserted 1.00
s2	Due to the strong coupling effect, modification of the gravitational force is source-dependent, and for lighter sources sets in at shorter distances.	result 0.78	0.66	0.10	asserted 1.00
s3	This universal feature makes modified gravity theories predictive and potentially testable not only by cosmological observations, but also by precision gravitational measurements at scales much shorter than the current cosmological horizon.	interpretation 1.00	0.61	0.23	asserted 0.57
s4	We give a simple parametrization of consistent large distance modified gravity theories and their predicted deviations from the Einsteinian metric near the gravitating sources.	contribution 0.97	0.92	0.10	asserted 0.99

What kind of paper the classifier reports this is: theoretical result 1.00 · evidence from proof or derivation 0.94.

What was examined, and what was not

sources read

arXiv listing abstract v1

not examined

full text
figures and tables
references and citing sentences
relations to other papers

levels run

P abstract

not run

S sections
T body sentences
C citations
R cross-paper relations

Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

References

Works cited (23)

[22]

M.A. Luty, M. Porrati and R. Rattazzi, JHEP 0309 (2003) 029, [hep-th/0303116]; D. Gor- bunov, K. Koyama and S. Sibiryakov, [hep-th/0512097]; C. Charmo usis, R. Gregory, N. Kaloper and A. Padilla, [hep-th/0604086]

View on Pith Pith review arXiv 2003
[16]

A. Gruzinov, New Astron. 10 (2005) 311; [astro-ph/0112246]

View on Pith Pith review arXiv 2005
[18]

G. Gabadadze and A. Iglesias, Phys. Rev. D72 (2005) 084024, [hep-th/ 0407049]; Phys. Lett. B 632 (2006) 622, [hep-th/0508201]

View on Pith Pith review arXiv 2005
[1]

A. G. Riess et al. [Supernova Search Team Collaboration], Astron. J. 116, 1009 (1998) [arXiv:astro-ph/9805201]; S. Perlmutter et al. [Supernova Cosmology Project Collaboration], Astrophys. J. 517, 565 (1999) [arXiv:astro-ph/9812133]

View on Pith Pith review arXiv 1998
[2]

C. Deﬀayet, G. Dvali and G. Gabadadze, Phys. Rev. D 65 , 044023 (2002) [astro-ph/0105068]

View on Pith Pith review arXiv 2002
[3]

G. Dvali, G. Gabadadze and M. Porrati, Phys. Lett. B 485, 208 (2000) [hep-th/0005016]. 9

View on Pith Pith review arXiv 2000
[4]

G. Dvali, G. Gabadadze, X. Hou, E. Sefusatti, Phys. Rev. D67 (2003) 044019; [hep-th/0111266]

View on Pith Pith review arXiv 2003
[5]

G. Dvali and G. Gabadadze, Phys. Rev. D 63, 065007 (2001) [hep-th/0008054]

View on Pith Pith review arXiv 2001
[6]

I. Antoniadis, R. Minasian and P. Vanhove, Nucl. Phys. B648 (2003) 69; [hep-th/0209030]

View on Pith Pith review arXiv 2003
[7]

D. G. Boulware and S. Deser., Phys. Rev. D6, 3368 (1972)

View on Pith 1972
[8]

G. Gabadadze and A. Gruzinov, Phys. Rev. D72 (2005) 124007; [hep-th/0312074]

View on Pith Pith review arXiv 2005
[9]

C. Deﬀayet, G. Dvali, G. Gabadadze and A. I. Vainshtein, Phys. R ev. D 65, 044026 (2002) [hep-th/0106001]

View on Pith Pith review arXiv 2002
[10]

G. Dvali, A. Gruzinov and M. Zaldarriaga, Phys. Rev. D 68 , 024012 (2003) [hep-ph/0212069]

View on Pith Pith review arXiv 2003
[11]

G. Dvali, Phys. Scripta T117 (2005) 92; [hep-th/0501157]; G.Dvali, A. Nunez and S. Solganik, unpublished

View on Pith Pith review arXiv 2005
[12]

H. van Dam and M. Veltman, Nucl. Phys. B22, 397 (1970) . V. I. Zakharov, JETP Lett. 12, 312 (1970)

View on Pith 1970
[13]

A. I. Vainshtein, Phys. Lett. B 39 , 393 (1972)

View on Pith 1972
[14]

C. Deﬀayet, Phys. Lett. B 502 , 199 (2001) [hep-th/0010186]

View on Pith Pith review arXiv 2001
[15]

N. Arkani-Hamed, H. Georgi and M.D. Schwartz, Annals Phys. 305, 96 (2003); [hep-th/0210184]

View on Pith Pith review arXiv 2003
[17]

A. Lue and G. Starkman, Phys. Rev. D 67 , 064002 (2003) [astro-ph/0212083]

View on Pith Pith review arXiv 2003
[19]

E. Adelberger (2002). Private communication; T.W. Murphy, Jr., E.G. Adelberger, J.D. Strasburg and C.W. Stubbs, ‘APOLLO: Multiplexed Lunar Laser Ranging’, at http://physics.ucsd.edu/∼tmurphy/apollo/doc/multiplex.pdf; 10

View on Pith 2002
[20]

G. Dvali and M. Turner, [astro-ph/0301510]

View on Pith Pith review arXiv
[21]

A. Lue, R. Scoccimarro and G. Starkman, Phys. Rev. D69 (2004) 044005; [astro-ph/0307034]

View on Pith Pith review arXiv 2004
[23]

C. Deﬀayet, G. Gabadadze and A. Iglesias, JCAP 0608 (2006) 0 12. 11

View on Pith 2006

Forward citations

Cited by 30 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

Bi-galileon theory I: motivation and formulation
hep-th 2010-07 conditional novelty 7.0 of 10

The paper constructs the most general two-field galileon theory, shows a braneworld model reduces to it in a decoupling limit, and derives a geometric stability criterion for its maximally symmetric vacua.
Self-Consistent Cosmological Simulations of DGP Braneworld Gravity
astro-ph.CO 2009-05 conditional novelty 7.0 of 10

A full non-linear N-body simulation of DGP gravity shows the brane bending mode's self-interactions restore General Relativity in dense regions, weakening the model's predicted deviations from standard gravity on quas...
Redshift space distortions in the presence of non-minimally coupled dark matter
astro-ph.CO 2019-08 conditional novelty 6.0 of 10

In dark matter-dark energy coupling models, the Kaiser formula gains a coupling-dependent term, so redshift-space distortions measure an effective growth rate that differs from the true matter growth rate, with Euclid...
A Spin-2 Conjecture on the Swampland
hep-th 2018-11 conditional novelty 6.0 of 10

A massive spin-two field forces an infinite tower of states at a cutoff of order m times the Planck mass divided by the spin-two interaction scale, which is the Weak Gravity Conjecture applied to the field's Stueckelb...
Cosmological perturbations and structure formation in nonlocal infrared modifications of general relativity
astro-ph.CO 2014-03 conditional novelty 6.0 of 10

The R□⁻²R nonlocal dark energy model has stable perturbations and predicts scale-independent deviations from general relativity of a few percent in structure growth and lensing, with growth index γ ≈ 0.53.

Show 25 more citing papers

Non-local gravity and dark energy
hep-th 2014-02 conditional novelty 6.0 of 10

A one-parameter nonlocal extension of general relativity generates dynamical dark energy and predicts w approximately -1.14, consistent with current data.
Phantom dark energy from non-local infrared modifications of General Relativity
hep-th 2013-07 conditional novelty 6.0 of 10

A non-local infrared modification of Einstein's equations yields dynamical dark energy with a phantom equation of state w0 approximately -1.04, after one mass parameter is fitted to the observed dark energy density.
A non-local theory of massive gravity
hep-th 2013-05 conditional novelty 6.0 of 10

A covariant non-local massive gravity theory is constructed whose scalar ghost has mass equal to the graviton mass and decouples as m goes to zero, making its vacuum instability negligible for m of order H0.
On ghosts in theories of self-interacting massive spin-2 particles
hep-th 2011-07 conditional novelty 6.0 of 10

A helicity-decomposition analysis argues that Einstein-type self-interactions of a massive spin-2 field always introduce ghost instabilities, while a two-parameter family of non-Einsteinian cubic interactions is ghost-free.
N-Body Simulations of DGP and Degravitation Theories
astro-ph.CO 2009-03 conditional novelty 6.0 of 10

N-body simulations of DGP and cascading/degravitation gravity show enhanced clustering relative to standard cosmology, with the standard halofit formula overpredicting the boost on nonlinear scales and a retuned versi...
Observational Evidence for Cosmological-Scale Extra Dimensions
astro-ph 2008-12 conditional novelty 6.0 of 10

A single extra scalar force from cosmological-scale extra dimensions, with a crossover length of 300 to 600 Mpc, is argued to explain four independent two-sigma excesses in structure growth and the missing large-angle...
Non-linear evolution of f(R) cosmologies II: power spectrum
astro-ph 2008-07 accept novelty 6.0 of 10

First cosmological simulations with the chameleon mechanism show it suppresses f(R) power spectrum enhancements at small scales by up to a factor of four, while leaving measurable signals at intermediate scales.
Cascading Gravity and Degravitation
hep-th 2007-12 conditional novelty 6.0 of 10

A cascading brane model of gravity is shown, at linear order, to be ghost-free once the brane is regularized to finite thickness, and to have the propagator behavior needed for degravitation.
Quantum Break-Time of de Sitter
hep-th 2017-01 conditional novelty 5.0 of 10

De Sitter space has a finite quantum lifetime of order its Hubble radius times its horizon area in Planck units, after which the classical metric description fails.
Non-local gravity and comparison with observational datasets. II. Updated results and Bayesian model comparison with $\Lambda$CDM
astro-ph.CO 2016-02 conditional novelty 5.0 of 10

With Planck 2015 plus BAO, JLA and growth data, the RT non-local gravity model is statistically indistinguishable from ΛCDM, while the RR model is disfavored unless a high local H0 prior is added.
Cosmological dynamics and dark energy from non-local infrared modifications of gravity
hep-th 2013-11 conditional novelty 5.0 of 10

A non-local infrared modification of gravity with one mass parameter reproduces the observed dark energy density and predicts a phantom equation of state, w0 about -1.042 and wa about -0.020.
Bi-galileon theory II: phenomenology
hep-th 2010-08 reject novelty 5.0 of 10

A bi-galileon self-acceleration model was proposed as pathology-free, but the paper's appended erratum argues that no such model can simultaneously satisfy all the stated consistency conditions.
Physics of Trans-Planckian Gravity
hep-th 2010-06 conditional novelty 5.0 of 10

Ghost-free gravity cannot weaken below Einstein's before strong coupling, and black hole formation makes sub-Planckian distances unobservable, leaving no physical domain for asymptotically safe gravity.
Self-Completeness of Einstein Gravity
hep-th 2010-05 conditional novelty 5.0 of 10

Pure Einstein gravity may be ultraviolet-complete on its own, because black hole formation blocks access to sub-Planckian distances and turns trans-Planckian quantum states into classical black holes.
Lessons from the decoupling limit of Horava gravity
hep-th 2010-03 conditional novelty 5.0 of 10

In the decoupling limit of 'healthy' Horava gravity the extra scalar is strongly coupled below the derivative-expansion cutoff unless a new low Lorentz-violating scale is inserted by hand, and it mediates a constant f...
Cosmological Constraints on DGP Braneworld Gravity with Brane Tension
astro-ph.CO 2009-05 conditional novelty 5.0 of 10

Joint CMB, supernova, H0 and galaxy-ISW data show no preference for DGP braneworld gravity on either branch, requiring H0 r_c > 3 at 95% confidence.
Constraining Interactions in Cosmology's Dark Sector
astro-ph 2008-08 conditional novelty 5.0 of 10

Combined CMB, large-scale structure, and supernova data bound dark matter's coupling to a quintessence field to under 7% of gravity and a Yukawa self-interaction to under 5% of gravity at 10 Mpc.
Probing Gravity with Spacetime Sirens
astro-ph 2007-08 conditional novelty 5.0 of 10

A gravitational-wave Hubble diagram from LISA black hole mergers could, in principle, reveal large-distance leakage of gravity into extra dimensions, though the authors note the effect may be suppressed in the DGP mod...
Degravitation of the Cosmological Constant and Graviton Width
hep-th 2007-03 conditional novelty 5.0 of 10

Degravitating the cosmological constant requires the graviton to be massive or a resonance, which brings extra polarizations and ghost instabilities that constrain the allowed filter exponent to α < 1/2.
Nonlocal gravity. Conceptual aspects and cosmological predictions
hep-th 2017-12 conditional novelty 4.0 of 10

The RR nonlocal-gravity model fits current cosmological data about as well as ΛCDM while yielding a higher Hubble constant and a nonzero neutrino mass sum, though that mass sum is a fitted parameter rather than a prediction.
Species and Strings
hep-th 2010-04 conditional novelty 4.0 of 10

Weakly coupled string theory is argued to behave as a theory of N = 1/g_s^2 particle species, with the species scale, not the Planck length, setting the shortest resolvable distance.
Nonlocal Infrared Modifications of Gravity. A Review
hep-th 2016-06 conditional novelty 3.0 of 10

Two nonlocal gravity models built from R □⁻² R reproduce the observed cosmic acceleration and fit CMB, BAO, supernova and growth data at a level statistically comparable to ΛCDM with the same parameter count.
Theoretical Aspects of Massive Gravity
hep-th 2011-05 accept novelty 3.0 of 10

Massive gravity can be organized as a consistent effective field theory with a raised cutoff and no Boulware-Deser ghost, though a UV completion remains unknown.
Photon and Graviton Mass Limits
hep-ph 2008-09 accept novelty 3.0 of 10

The photon Compton wavelength must exceed roughly 1.3 astronomical units, and any graviton Compton wavelength must be comparable to the radius of the visible universe.
Ghosts in the self-accelerating universe
hep-th 2007-09 conditional novelty 2.0 of 10

The self-accelerating DGP braneworld, the leading modified-gravity alternative to dark energy, carries a ghost that survives every simple repair attempted in the literature.

How the literature uses it

44 arXiv papers cite this in 70 sentences

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

Papers citing it · 54 sentences without a confident label

Uses its method or tool 1 paper

This is particularly useful, since following [ref] , we can integrate out the additional helicities and write down an effective equation for $h_μν$.

Quantum Break-Time of de Sitter · Mapping de Sitter on a graviton mass · 0.87

Uses its data or values 1 paper

In such a setting, experiments directly constrain $m < 10^-22$ eV [ref] , while in [ref] it was argued that a generic IR modification of gravity is constrained to have $m < 10^-34$ eV.

A Spin-2 Conjecture on the Swampland · Discussion · 0.91

Compares with it 1 paper

Thus our set up escapes the strong coupling effect encountered in [ref] .

Scalar modifications to gravity from unparticle effects may be testable · Introduction · 0.80

Cites it as support 5 papers

We have observed that $η$ is a gravitational coupling and any such coupling can only increase from its Einstein value in unitary theories [ref] .

Unitarity constraints on the ratio of shear viscosity to entropy density in higher derivative gravity · Introduction · 0.99
For a unitary theory, all of the couplings must remain positive at all energy scales [ref] ; meaning that the propagator can only increase relative to its Einstein value.

Bounds on Black Hole Entropy in Unitary Theories of Gravity · The entropy of black holes in Einstein gravity is minimal · 0.97
For a ghost-free theory, all of the couplings must remain positive at all energy scales [ref] ; meaning that the propagator can only increase relative to its Einstein value.

Proof of a universal lower bound on the shear viscosity to entropy density ratio · Introduction · 0.98

Cites it as background 8 papers

The first successful model of this type was proposed in [ref] (see also [ref] for earlier related ideas), and is defined by the non-local equation of motion -m^2/3$R$^T=8πG , where the superscript T denotes the operation of taking the transverse part of a tensor (which is itself a non-local operation).

Perturbative loop corrections and nonlocal gravity · Introduction · 0.84
In a line of research, nonlocal gravity models are constructed with the motivation to write massive term without breaking the gauge invariance of massless theory [ref] .

Modified Gravity Corrections in Fundamental Orbital Frequencies in Kerr Spacetime · INTRODUCTION · 0.92
Numerous examples of this line of thinking can be found in the literature [ref] .

Instabilities in tensorial nonlocal gravity · Introduction · 0.86

Discussion

Disagree with the review, or know something it missed? Leave a comment, highlight any passage above to comment on it, or challenge this review formally.

[1] [22]

M.A. Luty, M. Porrati and R. Rattazzi, JHEP 0309 (2003) 029, [hep-th/0303116]; D. Gor- bunov, K. Koyama and S. Sibiryakov, [hep-th/0512097]; C. Charmo usis, R. Gregory, N. Kaloper and A. Padilla, [hep-th/0604086]

View on Pith Pith review arXiv 2003

[2] [16]

A. Gruzinov, New Astron. 10 (2005) 311; [astro-ph/0112246]

View on Pith Pith review arXiv 2005

[3] [18]

G. Gabadadze and A. Iglesias, Phys. Rev. D72 (2005) 084024, [hep-th/ 0407049]; Phys. Lett. B 632 (2006) 622, [hep-th/0508201]

View on Pith Pith review arXiv 2005

[4] [1]

A. G. Riess et al. [Supernova Search Team Collaboration], Astron. J. 116, 1009 (1998) [arXiv:astro-ph/9805201]; S. Perlmutter et al. [Supernova Cosmology Project Collaboration], Astrophys. J. 517, 565 (1999) [arXiv:astro-ph/9812133]

View on Pith Pith review arXiv 1998

[5] [2]

C. Deﬀayet, G. Dvali and G. Gabadadze, Phys. Rev. D 65 , 044023 (2002) [astro-ph/0105068]

View on Pith Pith review arXiv 2002

[6] [3]

G. Dvali, G. Gabadadze and M. Porrati, Phys. Lett. B 485, 208 (2000) [hep-th/0005016]. 9

View on Pith Pith review arXiv 2000

[7] [4]

G. Dvali, G. Gabadadze, X. Hou, E. Sefusatti, Phys. Rev. D67 (2003) 044019; [hep-th/0111266]

View on Pith Pith review arXiv 2003

[8] [5]

G. Dvali and G. Gabadadze, Phys. Rev. D 63, 065007 (2001) [hep-th/0008054]

View on Pith Pith review arXiv 2001

[9] [6]

I. Antoniadis, R. Minasian and P. Vanhove, Nucl. Phys. B648 (2003) 69; [hep-th/0209030]

View on Pith Pith review arXiv 2003

[10] [7]

D. G. Boulware and S. Deser., Phys. Rev. D6, 3368 (1972)

View on Pith 1972

[11] [8]

G. Gabadadze and A. Gruzinov, Phys. Rev. D72 (2005) 124007; [hep-th/0312074]

View on Pith Pith review arXiv 2005

[12] [9]

C. Deﬀayet, G. Dvali, G. Gabadadze and A. I. Vainshtein, Phys. R ev. D 65, 044026 (2002) [hep-th/0106001]

View on Pith Pith review arXiv 2002

[13] [10]

G. Dvali, A. Gruzinov and M. Zaldarriaga, Phys. Rev. D 68 , 024012 (2003) [hep-ph/0212069]

View on Pith Pith review arXiv 2003

[14] [11]

G. Dvali, Phys. Scripta T117 (2005) 92; [hep-th/0501157]; G.Dvali, A. Nunez and S. Solganik, unpublished

View on Pith Pith review arXiv 2005

[15] [12]

H. van Dam and M. Veltman, Nucl. Phys. B22, 397 (1970) . V. I. Zakharov, JETP Lett. 12, 312 (1970)

View on Pith 1970

[16] [13]

A. I. Vainshtein, Phys. Lett. B 39 , 393 (1972)

View on Pith 1972

[17] [14]

C. Deﬀayet, Phys. Lett. B 502 , 199 (2001) [hep-th/0010186]

View on Pith Pith review arXiv 2001

[18] [15]

N. Arkani-Hamed, H. Georgi and M.D. Schwartz, Annals Phys. 305, 96 (2003); [hep-th/0210184]

View on Pith Pith review arXiv 2003

[19] [17]

A. Lue and G. Starkman, Phys. Rev. D 67 , 064002 (2003) [astro-ph/0212083]

View on Pith Pith review arXiv 2003

[20] [19]

E. Adelberger (2002). Private communication; T.W. Murphy, Jr., E.G. Adelberger, J.D. Strasburg and C.W. Stubbs, ‘APOLLO: Multiplexed Lunar Laser Ranging’, at http://physics.ucsd.edu/∼tmurphy/apollo/doc/multiplex.pdf; 10

View on Pith 2002

[21] [20]

G. Dvali and M. Turner, [astro-ph/0301510]

View on Pith Pith review arXiv

[22] [21]

A. Lue, R. Scoccimarro and G. Starkman, Phys. Rev. D69 (2004) 044005; [astro-ph/0307034]

View on Pith Pith review arXiv 2004

[23] [23]

C. Deﬀayet, G. Gabadadze and A. Iglesias, JCAP 0608 (2006) 0 12. 11

View on Pith 2006