Multimetric gravity via massive gravity

Khosravi, Nima; Rahmanpour, Nafiseh; Sepangi, H. R.; Shahidi, Shahab

doi:10.1103/physrevd.85.024049

Cited by 54 publications

(65 citation statements)

References 26 publications

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“…One possibility is to let the background metric be dynamical, and consider a bi-metric theory [658,[717][718][719] (or even a multi-metric theory [655,[719][720][721]), leading to different cosmological solutions [620,[722][723][724][725][726][727][728][729][730][731][732][733][734][735]. Another possibility is to let the graviton mass itself be a field [736][737][738] or to couple in additional fields [739][740][741][742][743] (for instance galileon scalar fields [559,561,744]).…”

Section: Self-accelerating Solutions In the Decoupling Limitmentioning

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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Section: Self-accelerating Solutions In the Decoupling Limitmentioning

confidence: 99%

Beyond the cosmological standard model

et al. 2015

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“…In this paper we will work mostly with this Hassan-Rosen bimetric theory. For related work, see [40][41][42][43][44][45][46][47][48][49][50][51][52].…”

Section: Background To Bimetric Theoriesmentioning

confidence: 99%

On consistent theories of massive spin-2 fields coupled to gravity

Hassan

Schmidt-May

Strauss

2013

J. High Energ. Phys.

123

177

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We consider the issues that arise out of interpreting the ghost-free bimetric theory as a theory of a spin-2 field coupled to gravity. This requires identifying a gravitational metric and parameterizing deviations of the resulting theory from general relativity. To this end, we first consider the most general bimetric backgrounds for which a massless and a massive spin-2 fluctuation exist, and we compute the most general expression for the Fierz-Pauli mass. These backgrounds coincide with solutions in general relativity. Based on this, we obtain nonlinear extensions of the massive and massless spin-2 fields. The background value of the nonlinear massive field parameterizes generic deviations of the bimetric theory from GR. It is also shown that the most natural nonlinear massless field does not have standard ghost-free matter couplings, and hence cannot represent the gravitational metric. However, an appropriate gravitational metric can still be identified in the weak gravity limit. Hence in the presence of other neutral spin-2 fields, the weak gravity limit is crucial for compatibility with general relativity. We also write down the action in terms of the nonlinear massive spin-2 field and obtain its ghost-free couplings to matter. The discussion is then generalized to multimetric theories.

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“…This generalization has been discussed before in Refs. [26,67,68], but all the cases studied in those references are pathological. Ref.…”

Section: Introductionmentioning

confidence: 99%

Cosmology with three interacting spin-2 fields

et al. 2016

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Theories of massive gravity with one or two dynamical metrics generically lack stable and observationally-viable cosmological solutions that are distinguishable from ΛCDM. We consider an extension to trimetric gravity, with three interacting spin-2 fields which are not plagued by the Boulware-Deser ghost. We systematically explore every combination with two free parameters in search of background cosmologies that are competitive with ΛCDM. For each case we determine whether the expansion history satisfies viability criteria, and whether or not it contains beyond-ΛCDM phenomenology. Among the many models we consider, there are only three cases that seem to be both viable and distinguishable from standard cosmology. One of the models has only one free parameter and displays a crossing from above to below the phantom divide. The other two provide scaling behavior, although they contain future singularities that need to be studied in more detail. These models possess interesting features that make them compelling targets for a full comparison to observations of both cosmological expansion history and structure formation.

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Multimetric gravity via massive gravity

Cited by 54 publications

References 26 publications

Beyond the cosmological standard model

Beyond the cosmological standard model

On consistent theories of massive spin-2 fields coupled to gravity

Cosmology with three interacting spin-2 fields

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