Modified Friedmann equation from nonminimally coupled theories of gravity

Bertolami, Orfeu; Páramos, Jorge

doi:10.1103/physrevd.89.044012

Cited by 72 publications

(54 citation statements)

References 51 publications

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“…The dynamical equation of massive particles in f (R) gravity assuming an explicit interaction between the scalar curvature and density of matter has been derived and it is shown that the presence of this coupling yields an extra force (Bertolami et al 2007). A study of the modification of Friedmann equation due to the inclusion of non-minimal coupling has been done and two ways are provided to handle the corresponding situation (Bertolami and Páramos 2014). A more general type of f (T ) gravity theory by introducing a nonminimal interaction of torsion with matter in the Lagrangian density has been constructed (Harko et al 2014).…”

Section: Introductionmentioning

confidence: 99%

A spherically symmetric null tetrads in non-minimal torsion-matter coupling extension of f(T) gravity

Nashed

2015

Astrophys Space Sci

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We construct a null tetrad from a non-diagonal spherically symmetric vierbein field, involving two unknown functions of radial coordinate r. This null tetrad is applied to the equations of motion of non-minimal torsionmatter coupling extension of f (T ) gravity. Exact vacuum solution with two constants of integration is obtained. The scalar torsion related to this special solution is constant. The energy of this solution is calculated using the Euclidean continuation method and the known value is derived. We also calculate the thermodynamical quantities of charged Schwarzschild spacetime and investigate the validity of the first law of thermodynamics and quantum statistical relation.

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Section: Introductionmentioning

confidence: 99%

A spherically symmetric null tetrads in non-minimal torsion-matter coupling extension of f(T) gravity

Nashed

2015

Astrophys Space Sci

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“…We applied BBN to constrain the parameter and found it should satisfy −0.141 < α < 0.09 or 1.000025 < α < 1.000046 to avoid conflicts with observations. Studies on the model proposed here, such as constraints from other astronomical observations or particle rate creation (see, for example, some related researches [47][48][49][50][51][52][53]), can be considered in the coming progresses.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Effects of quantum fluctuations of metric on the universe

Yang

2015

Chin. Sci. Bull.

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We consider a model of modified gravity from the nonperturbative quantization of a metric. We obtain the modified gravitational field equations and the modified conservational equations. We apply it to the FLRW spacetime and find that due to the quantum fluctuations a bounce universe can be obtained and a decelerated expansion can also possibly be obtained in a dark energy dominated epoch. We also discuss the effects of quantum fluctuations on inflation parameters (such as slowroll parameters, spectral index, and the spectrum of the primordial curvature perturbation) and find values of parameters in the comparing the predictions of inflation can also work to drive the current epoch of acceleration. We obtain the constraints on the parameter of the theory from the observation of the big bang nucleosynthesis.

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“…The motivation of this model stems from the fact that quadratic curvature corrections arise in the quantization of fields in curved spacetime [29,30], in approaches to quantum gravity based both on string theory [31,32] and on loop quantum gravity [33,34], and when GR is regarded as an effective theory of quantum gravity [35].…”

Section: Palatini Ricci-squared Theorymentioning

confidence: 99%

Microscopic wormholes and the geometry of entanglement

Olmo

Rubiera-García

2014

Eur. Phys. J. C

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It has recently been suggested that EinsteinRosen (ER) bridges can be interpreted as maximally entangled states of two black holes that form a complex EinsteinPodolsky-Rosen (EPR) pair. This relationship has been dubbed as the ER = EPR correlation. In this work, we consider the latter conjecture in the context of quadratic Palatini theory. An important result, which stems from the underlying assumptions as regards the geometry on which the theory is constructed, is the fact that all the charged solutions of the quadratic Palatini theory possess a wormhole structure. Our results show that spacetime may have a foamlike microstructure with wormholes generated by fluctuations of the quantum vacuum. This involves the spontaneous creation/annihilation of entangled particle-antiparticle pairs, existing in a maximally entangled state connected by a nontraversable wormhole. Since the particles are produced from the vacuum and therefore exist in a singlet state, they are necessarily entangled with one another. This gives further support to the ER = EPR claim.

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Modified Friedmann equation from nonminimally coupled theories of gravity

Cited by 72 publications

References 51 publications

A spherically symmetric null tetrads in non-minimal torsion-matter coupling extension of f(T) gravity

A spherically symmetric null tetrads in non-minimal torsion-matter coupling extension of f(T) gravity

Effects of quantum fluctuations of metric on the universe

Microscopic wormholes and the geometry of entanglement

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