Growth of matter perturbations in the bi-Galileons field model

Boumaza, Hamza; Nouicer, Khireddine

doi:10.1103/physrevd.100.124047

Cited by 24 publications

(26 citation statements)

References 96 publications

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“…Because of our normalization, the constant term can be taken to be equal to unity. In order to compare the model with the cosmological observations, we will estimate the best fit values of the parameters H 0 and δ by using the recent observational data on the Hubble parameter [138,139].…”

Section: Numerical Analysismentioning

confidence: 99%

Cosmological evolution and dark energy in osculating Barthel–Randers geometry

2021

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We consider the cosmological evolution in an osculating point Barthel–Randers type geometry, in which to each point of the space-time manifold an arbitrary point vector field is associated. This Finsler type geometry is assumed to describe the physical properties of the gravitational field, as well as the cosmological dynamics. For the Barthel–Randers geometry the connection is given by the Levi-Civita connection of the associated Riemann metric. The generalized Friedmann equations in the Barthel–Randers geometry are obtained by considering that the background Riemannian metric in the Randers line element is of Friedmann–Lemaitre–Robertson–Walker type. The matter energy balance equation is derived, and it is interpreted from the point of view of the thermodynamics of irreversible processes in the presence of particle creation. The cosmological properties of the model are investigated in detail, and it is shown that the model admits a de Sitter type solution, and that an effective cosmological constant can also be generated. Several exact cosmological solutions are also obtained. A comparison of three specific models with the observational data and with the standard $$\Lambda $$ Λ CDM model is also performed by fitting the observed values of the Hubble parameter, with the models giving a satisfactory description of the observations.

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Section: Numerical Analysismentioning

confidence: 99%

Cosmological evolution and dark energy in osculating Barthel–Randers geometry

2021

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“…This is obtained by taking β = 0 in the field equations. The observational data of the Hubble parameter together with their errors is also shown [92]. It can be seen from the figures that the non-minimal coupling between matter and geometry affects the cosmological behavior of the Universe at redshifts greater than z ∼ 2.…”

Section: Cosmological Consequencesmentioning

confidence: 96%

Non-minimal energy–momentum squared gravity

Shahidi

2021

Eur. Phys. J. C

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We consider a gravitational theory with an additional non-minimal coupling between baryonic matter fields and geometry. The coupling is second order in the energy momentum tensor and can be seen as a generalization of the energy–momentum squared gravity model. We will add a constraint through a Lagrange multiplier to ensure the conservation of the energy–momentum tensor. Background cosmological implications together with its dynamical system analysis will be investigated in details. Also we will consider the growth of matter perturbations at first order, and estimate the model parameter from observations on H and also $$f\sigma _8$$ f σ 8 . We will show that the model parameter should be small and positive in 2$$\sigma $$ σ confidence interval. The theory is shown to be in a good agreement with observational data.

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“…It is well-known that there are two choices for the perfect fluid matter Lagrangian, i.e. L m = −ρ and L m = p. These two For the Hubble parameter, we have also plotted the observational data together with their errors [168][169][170][171][172][173][174][175][176]. The CDM curve is depicted as a red solid curve choices lead to the same matter energy-momentum tensor in the case of Einstein's gravity.…”

Section: The Multiplicative Casementioning

confidence: 99%

Generalizing the coupling between geometry and matter: $$f\left( R,L_m,T\right) $$ gravity

Haghani

Harkó

2021

Eur. Phys. J. C

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We generalize and unify the $$f\left( R,T\right) $$ f R , T and $$f\left( R,L_m\right) $$ f R , L m type gravity models by assuming that the gravitational Lagrangian is given by an arbitrary function of the Ricci scalar R, of the trace of the energy–momentum tensor T, and of the matter Lagrangian $$L_m$$ L m , so that $$ L_{grav}=f\left( R,L_m,T\right) $$ L grav = f R , L m , T . We obtain the gravitational field equations in the metric formalism, the equations of motion for test particles, and the energy and momentum balance equations, which follow from the covariant divergence of the energy–momentum tensor. Generally, the motion is non-geodesic, and takes place in the presence of an extra force orthogonal to the four-velocity. The Newtonian limit of the equations of motion is also investigated, and the expression of the extra acceleration is obtained for small velocities and weak gravitational fields. The generalized Poisson equation is also obtained in the Newtonian limit, and the Dolgov–Kawasaki instability is also investigated. The cosmological implications of the theory are investigated for a homogeneous, isotropic and flat Universe for two particular choices of the Lagrangian density $$f\left( R,L_m,T\right) $$ f R , L m , T of the gravitational field, with a multiplicative and additive algebraic structure in the matter couplings, respectively, and for two choices of the matter Lagrangian, by using both analytical and numerical methods.

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Growth of matter perturbations in the bi-Galileons field model

Cited by 24 publications

References 96 publications

Cosmological evolution and dark energy in osculating Barthel–Randers geometry

Cosmological evolution and dark energy in osculating Barthel–Randers geometry

Non-minimal energy–momentum squared gravity

Generalizing the coupling between geometry and matter: $$f\left( R,L_m,T\right) $$ gravity

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