New kinetic interactions for massive gravity?

Rham, Claudia de; Matas, A.; Tolley, Andrew J.

doi:10.1088/0264-9381/31/16/165004

Cited by 73 publications

(170 citation statements)

References 52 publications

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“…5 These results may be viewed positively in two ways, on the one hand there do exist ghost-free matter couplings in the decoupling limit, and that is sufficient for validity of the EFT for energies E ≤ Λ. On the other hand the absence of any nonminimal matter coupling, like the absence of nonminimal kinetic terms [45], is a remarkable testament to the power of field theory consistency in determining unique interacting theories.…”

Section: Discussionmentioning

confidence: 99%

Vielbein to the rescue? Breaking the symmetric vielbein condition in massive gravity and multigravity

2015

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Nonminimal matter couplings have recently been considered in the context of massive gravity and multigravity. These couplings are free of the Boulware-Deser ghost in the decoupling limit and can thus be considered within an effective field theory setup. Beyond the decoupling limit the ghost was shown to reemerge in the metric formulation of the theory. Recently it was argued that this pathology is absent when formulated in terms of unconstrained vielbeins. We investigate this possibility and show that the BoulwareDeser ghost is always present beyond the decoupling limit in any dimension larger than 2. We also show that the metric and vielbein formulations have an identical ghost-free decoupling limit. Finally we extend these arguments to more generic multigravity theories and argue that for any dimension larger than 2 a ghost is also present in the vielbein formulation whenever the symmetric vielbein condition is spoiled and the equivalence with the metric formulation is lost.

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Section: Discussionmentioning

confidence: 99%

Vielbein to the rescue? Breaking the symmetric vielbein condition in massive gravity and multigravity

2015

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“…41 This is apparently a choice, naïvely we could also introduce new derivative interactions. Indeed, there do exist derivative interactions whose leading terms in a small-field expansion ('pseudo-linear' terms) are ghost free [678][679][680][681], but they cannot be consistently extended to the full non-linear theory [682,683]. Therefore, the Einstein-Hilbert term is the unique nonlinear interaction term involving derivatives.…”

Section: Nonlinear Massive Gravitymentioning

confidence: 99%

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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“…The question of the existence of a full non-linear theory with derivative interactions different from the one presented above, which arises from a field redefinition, is still open. There have been arguments claiming that this is not possible [63,64], although some new interactions were found in the pseudo-linear regime [65].…”

Section: Mixing With Spin-2 Fieldsmentioning

confidence: 99%

Field redefinitions in theories beyond Einstein gravity using the language of differential forms

2017

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We study the role of field redefinitions in general scalar-tensor theories. In particular, we first focus on the class of field redefinitions linear in the spin-2 field and involving derivatives of the spin-0 mode, generically known as disformal transformations. We start by defining the action of a disformal transformation in the tangent space. Then, we take advantage of the great economy of means of the language of differential forms to compute the full transformation of Horndeski's theory under general disformal transformations. We obtain that Horndeski's action maps onto itself modulo a reduced set of non-Horndeski Lagrangians. These new Lagrangians are found to be invariant under disformal transformation that depend only in the first derivatives of the scalar. Moreover, these combinations of Lagrangians precisely appear when expressing in our basis the constraints of the recently proposed Extended Scalar-Tensor (EST) theories. These results allow us to classify the different orbits of scalar-tensor theories invariant under particular disformal transformations, namely the special disformal, kinetic disformal and disformal Horndeski orbits. In addition, we consider generalizations of this framework. We find that there are possible well-defined extended disformal transformations that have not been considered in the literature. However, they generically cannot link Horndeski theory with EST theories. Finally, we study further generalizations in which extra fields with different spin are included. These field redefinitions can be used to connect different gravity theories such as multi-scalar-tensor theories, generalized Proca theories and bi-gravity. We discuss how the formalism of differential forms could be useful for future developments in these lines.PACS numbers: 04.50. Kd, 98.80.Cq, 95.36.+x,

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New kinetic interactions for massive gravity?

Cited by 73 publications

References 52 publications

Vielbein to the rescue? Breaking the symmetric vielbein condition in massive gravity and multigravity

Vielbein to the rescue? Breaking the symmetric vielbein condition in massive gravity and multigravity

Beyond the cosmological standard model

Field redefinitions in theories beyond Einstein gravity using the language of differential forms

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