Gravity with auxiliary fields

Pani, Paolo; Sotiriou, Thomas P.; Vernieri, Daniele

doi:10.1103/physrevd.88.121502

Cited by 59 publications

(99 citation statements)

References 29 publications

(54 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although such theories are not a priory ruled out, they can lead to phenomenological problems (see Ref. [74] for a discussion of such terms in the gravitational equations).…”

Section: A Matter-scalar Interactionmentioning

confidence: 99%

Transforming gravity: From derivative couplings to matter to second-order scalar-tensor theories beyond the Horndeski Lagrangian

2014

View full text Add to dashboard Cite

We study the structure of scalar-tensor theories of gravity based on derivative couplings between the scalar and the matter degrees of freedom introduced through an effective metric. Such interactions are classified by their tensor structure into conformal (scalar), disformal (vector) and extended disformal (traceless tensor), as well as by the derivative order of the scalar field. Relations limited to first derivatives of the field ensure second order equations of motion in the Einstein frame and hence the absence of Ostrogradski ghost degrees of freedom. The existence of a mapping to the Jordan frame is not trivial in the general case, and can be addressed using the Jacobian of the frame transformation through its eigenvalues and eigentensors. These objects also appear in the study of different aspects of such theories, including the metric and field redefinition transformation of the path integral in the quantum mechanical description. Although sane in the Einstein frame, generic disformally coupled theories are described by higher order equations of motion in the Jordan frame. This apparent contradiction is solved by the use of a hidden constraint: the contraction of the metric equations with a Jacobian eigentensor provides a constraint relation for the higher field derivatives, which allows one to express the dynamical equations in a second order form. This signals a loophole in Horndeski's theorem and allows one to enlarge the set of scalar-tensor theories which are Ostrogradski-stable. The transformed Gauss-Bonnet terms are also discussed for the simplest conformal and disformal relations.PACS numbers: 04.50. Kd, 98.80.Cq, 95.36.+x,

show abstract

“…Although such theories are not a priory ruled out, they can lead to phenomenological problems (see Ref. [74] for a discussion of such terms in the gravitational equations).…”

Section: A Matter-scalar Interactionmentioning

confidence: 99%

Transforming gravity: From derivative couplings to matter to second-order scalar-tensor theories beyond the Horndeski Lagrangian

2014

View full text Add to dashboard Cite

show abstract

“…One other approach is to modify Einstein's equations by introducing auxiliary fields (see e.g. [180,181]). …”

Section: Plmentioning

confidence: 99%

Beyond the cosmological standard model

et al. 2015

View full text Add to dashboard Cite

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.

show abstract

“…It is to be mentioned that when we choose c 3 equals to zero, this case satisfies the conservation equation (33). The corresponding Lagrangian becomes…”

Section: Noether Symmetries and F (G T ) Gravitymentioning

confidence: 99%

Some exact solutions in f(𝒢,T) gravity via Noether symmetries

Shamir

Ahmad

2017

Mod. Phys. Lett. A

View full text Add to dashboard Cite

This paper is devoted to investigate the recently proposed modified Gauss-Bonnet f (G, T ) gravity, with G, the Gauss-Bonnet term, coupled with T , the trace of energy-momentum tensor. We have used the Noether symmetry methodology to discuss some cosmologically important f (G, T ) gravity models with anisotropic background. In particular, the Noether symmetry equations for modified f (G, T ) gravity are reported for locally rotationally symmetric Bianchi type I universe. Explicitly, two models have been proposed to explore the exact solutions and the conserved quantities. It is concluded that the specific models of modified Gauss-Bonnet gravity may be used to reconstruct ΛCDM cosmology without involving any cosmological constant.

show abstract

Gravity with auxiliary fields

Cited by 59 publications

References 29 publications

Transforming gravity: From derivative couplings to matter to second-order scalar-tensor theories beyond the Horndeski Lagrangian

Transforming gravity: From derivative couplings to matter to second-order scalar-tensor theories beyond the Horndeski Lagrangian

Beyond the cosmological standard model

Some exact solutions in f(𝒢,T) gravity via Noether symmetries

Contact Info

Product

Resources

About