Stability and superluminality of spherical DBI Galileon solutions

Goon, Garrett; Hinterbichler, Kurt; Trodden, Mark

doi:10.1103/physrevd.83.085015

Cited by 84 publications

(81 citation statements)

References 36 publications

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“…In particular, this means that the earlier conclusions about superluminality [465] and (non)-analyticity persist. While this Lagrangian has an infinite number of terms when thought of as a series as in (6.12), the relative coefficients of these terms are fixed by symmetry.…”

Section: Generalizationsmentioning

confidence: 88%

Beyond the cosmological standard model

et al. 2015

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After a decade and a half of research motivated by the accelerating universe, theory and experiment have a reached a certain level of maturity. The development of theoretical models beyond Λ or smooth dark energy, often called modified gravity, has led to broader insights into a path forward, and a host of observational and experimental tests have been developed. In this review we present the current state of the field and describe a framework for anticipating developments in the next decade. We identify the guiding principles for rigorous and consistent modifications of the standard model, and discuss the prospects for empirical tests.We begin by reviewing recent attempts to consistently modify Einstein gravity in the infrared, focusing on the notion that additional degrees of freedom introduced by the modification must "screen" themselves from local tests of gravity. We categorize screening mechanisms into three broad classes: mechanisms which become active in regions of high Newtonian potential, those in which first derivatives of the field become important, and those for which second derivatives of the field are important. Examples of the first class, such as f (R) gravity, employ the familiar chameleon or symmetron mechanisms, whereas examples of the last class are galileon and massive gravity theories, employing the Vainshtein mechanism. In each case, we describe the theories as effective theories and discuss prospects for completion in a more fundamental theory. We describe experimental tests of each class of theories, summarizing laboratory and solar system tests and describing in some detail astrophysical and cosmological tests. Finally, we discuss prospects for future tests which will be sensitive to different signatures of new physics in the gravitational sector.The review is structured so that those parts that are more relevant to theorists vs. observers/experimentalists are clearly indicated, in the hope that this will serve as a useful reference for both audiences, as well as helping those interested in bridging the gap between them.

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Section: Generalizationsmentioning

confidence: 88%

Beyond the cosmological standard model

et al. 2015

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“…One may also wish to search for the equivalent to the pure dRGT massive gravity solutions which display flat, approximately FRW cosmological solutions at the cost of an inhomogeneous Stückelberg sector as in [25,32], about which the kinetic terms for scalar perturbations no longer vanish [33,35]. It will also be interesting to ask whether the fluctuations of the Galileon around these accelerating solutions can be kept subluminal, in contrast to the situation around flat space [31].…”

Section: Discussionmentioning

confidence: 99%

Cosmological perturbations of massive gravity coupled to DBI Galileons

Andrews¹,

Hinterbichler²,

Stokes³

et al. 2013

Class. Quantum Grav.

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Certain scalar fields with higher derivative interactions and novel classical and quantum mechanical properties -the Galileons -can be naturally covariantized by coupling to nonlinear massive gravity in such a way that their symmetries and number of degrees of freedom are unchanged. We study the propagating degrees of freedom in these models around cosmologically interesting backgrounds. We identify the conditions necessary for such a theory to remain ghost free, and consider when tachyonic instabilities can be avoided. We show that on the self-accelerating branch of solutions, the kinetic terms for the vector and scalar modes of the massive graviton vanish, as in the case of pure massive gravity.

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“…Despite the fact that the Galileon exhibits a broad and interesting phenomenology, they witness a potentially worrying phenomenon, namely the fluctuations of the Galileon field can propagate superluminally in the regime of interest [16,65,66]. Since the Galileon was introduced as an extention of the decoupling limit of DGP-gravity, the DGP model shares the same phenomenon of superluminal fluctuations [67].…”

Section: Jhep07(2013)067mentioning

confidence: 99%

Superluminality in the Bi- and Multi-Galileon

Fromont

Rham

Heisenberg

et al. 2013

J. High Energ. Phys.

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We re-explore the Bi-and Multi-Galileon models with trivial asymptotic conditions at infinity and show that propagation of superluminal fluctuations is a common and unavoidable feature of these theories, unlike previously claimed in the literature. We show that all Multi-Galileon theories containing a Cubic Galileon term exhibit superluminalities at large distances from a point source, and that even if the Cubic Galileon is not present one can always find sensible matter distributions in which there are superluminal modes at large distances. In the Bi-Galileon case we explicitly show that there are always superluminal modes around a point source even if the Cubic Galileon is not present. Finally, we briefly comment on the possibility of avoiding superluminalities by modifying the asymptotic conditions at infinity.

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Stability and superluminality of spherical DBI Galileon solutions

Cited by 84 publications

References 36 publications

Beyond the cosmological standard model

Beyond the cosmological standard model

Cosmological perturbations of massive gravity coupled to DBI Galileons

Superluminality in the Bi- and Multi-Galileon

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