Multiple field modified gravity and localized energy in teleparallel framework

Abedi, Habib; Saltı, Mustafa

doi:10.1007/s10714-015-1935-z

Cited by 31 publications

(14 citation statements)

References 61 publications

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“…Finally, one may also consider a more general class of modified teleparallel theories augmented with a non-minimally coupled scalar field [60][61][62][63], a Gauss-Bonnet term [64,65], a boundary term [66], combinations of those [67,68], or higher derivatives of the torsion scalar [69]. Additionally one may consider actions which are not a function of the torsion scalar (2), but of different contractions of the torsion tensor [70][71][72].…”

Section: Discussionmentioning

confidence: 99%

Dynamical systems approach and generic properties of f(T) cosmology

2017

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We present a systematic analysis of the dynamics of flat Friedmann-Lemaître-RobertsonWalker cosmological models with radiation and dust matter in generalized teleparallel f (T ) gravity. We show that the cosmological dynamics of this model are fully described by a function W (H) of the Hubble parameter, which is constructed from the function f (T ).After reducing the phase space to two dimensions, we derive the conditions on W (H) for the occurrence of de Sitter fixed points, accelerated expansion, crossing the phantom divide, and finite time singularities. Depending on the model parameters, it is possible to have a bounce (from contraction to expansion) or a turnaround (from expansion to contraction), but cyclic or oscillating scenarios are prohibited. As an illustration of the formalism we consider powern models, and show that these allow only one period of acceleration and no phantom divide crossing.

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Section: Discussionmentioning

confidence: 99%

Dynamical systems approach and generic properties of f(T) cosmology

2017

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“…[22], it is investigated the possibility to extend the Landau-Lifshitz complex to f (R) gravity for the Schwarzschild-de Sitter universe. Other modified prescriptions were developed in f (T ) theory [23][24][25] and in general higher-order theories of gravity [26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

Cosmological perturbations in gravitational energy–momentum complex

2019

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Starting from the energy-momentum of matter and gravitational field in the framework of General Relativity and Teleparallel Gravity, we obtain the energy-momentum complex in flat FRW spacetime. We show that the complex vanishes at background level considering the various prescriptions, that is the Einstein, Møller, Landau-Lifshitz and Bergmann ones. On the other hand, at level of linear cosmological perturbations, the energy-momentum complex is different from zero and coincides in the various prescriptions. Finally, we evaluate the gravitational energy for different cosmological epochs governed by non-relativistic matter, radiation, inflationary scalar fields and cosmological constant.

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“…The general form of an action, S, containing the torsion scalar T , a scalar field φ and the kinetic term X ≡ ∇ µ φ ∇ µ φ, is given by [54]…”

Section: A Review Of Teleparallel Gravitymentioning

confidence: 99%

Effective gravitational coupling in modified teleparallel theories

et al. 2018

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In the present study, we consider an extended form of teleparallel Lagrangian f (T, φ, X), as function of a scalar field φ, its kinetic term X and the torsion scalar T . We use linear perturbations to obtain the equation of matter density perturbations on sub-Hubble scales. The gravitational coupling is modified in scalar modes with respect to the one of General Relativity, albeit vector modes decay and do not show any significant effects. We thus extend these results by involving multiple scalar field models. Further, we study conformal transformations in teleparallel gravity and we obtain the coupling as the scalar field is non-minimally coupled to both torsion and boundary terms. Finally, we propose the specific model f (T, φ, X) = T + ∂µφ ∂ µ φ + ξT φ 2 . To check its goodness, we employ the observational Hubble data, constraining the coupling constant, ξ, through a Monte Carlo technique based on the Metropolis-Hastings algorithm. Hence, fixing ξ to its best-fit value got from our numerical analysis, we calculate the growth rate of matter perturbations and we compare our outcomes with the latest measurements and the predictions of the ΛCDM model. one way to tackle the dark energy problem is to consider new dynamical degrees of freedom inside the teleparallel scheme. For example, theories in which one replaces the Lagrangian by f (T ) functions, i.e. where the torsion scalar is replaced by a nonlinear function f (T ) [16][17][18][19][20][21], represent a viable framework naively inspired by f (R)gravity. This prescription can be even extended by a more general form based on f (T, B) functions in order to include both torsion and the boundary term [22,23]. This leads to a generalization of both f (R) and f (T ) classes of models and have been also studied as f (R, T ) in [24].In addition, one can use a scalar field responsible for the expansion, providing a scalar-tensor teleparallel dark energy acting as solution to the cosmic acceleration problem [26][27][28][29][30][31] and analogous to [25]. In this picture, the scalar field should be non-minimally coupled to gravity. This has been proved by working on renormalization of scalar-tensor theory and in the context of quantum corrections on curved spacetime [32][33][34][35][36][37][38].The most common way is to include a single scalar field, although this choice is not unique. Indeed, even though the use of single field models is consistent with data, the idea to consider multiple field models during inflation and the late-time expansion [39] is still possible. The multi-field can also be non-minimally coupled to gravity.

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Multiple field modified gravity and localized energy in teleparallel framework

Cited by 31 publications

References 61 publications

Dynamical systems approach and generic properties of f(T) cosmology

Dynamical systems approach and generic properties of f(T) cosmology

Cosmological perturbations in gravitational energy–momentum complex

Effective gravitational coupling in modified teleparallel theories

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