Reconstruction and exact solutions for cosmological perturbations from a generalized gravity theory
Sign Up to like & getrecommendations! Published in 2020 at "General Relativity and Gravitation"
DOI: 10.1007/s10714-020-02685-z
Abstract: Scalar and tensor cosmological perturbations during an inflationary universe scenario in the context of the a generalized gravity theory are studied. This analyze is carried out considering an ansatz on the variables associated to scalar… read more here.
Keywords: gravity theory; generalized gravity; cosmological perturbations; solutions cosmological ... See more keywords
Cosmological perturbations in the ΛCDM-like limit of a polytropic dark matter model
Sign Up to like & getrecommendations! Published in 2017 at "Astronomy and Astrophysics"
DOI: 10.1051/0004-6361/201630364
Abstract: It has recently been proposed that both dark matter (DM) and dark energy (DE) can be treated as a single component when they are considered in the context of a polytropic DM fluid with thermodynamical… read more here.
Keywords: perturbations cdm; dark matter; cdm like; polytropic ... See more keywords
Cosmological perturbations in Palatini formalism
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DOI: 10.1088/1475-7516/2021/03/006
Abstract: We investigate cosmological perturbations of scalar-tensor theories in Palatini formalism. First we introduce an action where the Ricci scalar is conformally coupled to a function of a scalar field and its kinetic term and there… read more here.
Keywords: palatini formalism; term; sound speed; formalism ... See more keywords
Entanglement entropy of cosmological perturbations for S-brane Ekpyrosis
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DOI: 10.1088/1475-7516/2021/03/094
Abstract: We calculate the entanglement entropy of scalar perturbations due to gravitational non-linearities present in any model of canonically-coupled, single-field ekpyrosis. Specifically, we focus on a recent model of improved ekpyrosis which is able to generate… read more here.
Keywords: entropy cosmological; perturbations brane; ekpyrosis; brane ekpyrosis ... See more keywords
Life of cosmological perturbations in modified dispersion relation models and the prospect of traveling primordial gravitational waves
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DOI: 10.1103/physrevd.100.123501
Abstract: We follow the life of a generic primordial perturbation mode (scalar or tensor) subject to modified dispersion relations (MDR), as its proper wavelength is stretched by expansion. A necessary condition ensuring that travelling waves can… read more here.
Keywords: life cosmological; life; gravity; modified dispersion ... See more keywords
Running of the spectrum of cosmological perturbations in string gas cosmology
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DOI: 10.1103/physrevd.96.123513
Abstract: We compute the running of the spectrum of cosmological perturbations in String Gas Cosmology, making use of a smooth parametrization of the transition between the early Hagedorn phase and the later radiation phase. We find… read more here.
Keywords: spectrum cosmological; cosmology; perturbations string; cosmological perturbations ... See more keywords
Cosmological perturbations in the entangled inflationary universe
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DOI: 10.1103/physrevd.97.066018
Abstract: In this paper it is presented the model of a multiverse made up of universes which are created in entangled pairs that conserve the total momentum conjugated to the scale factor. For the background spacetime… read more here.
Keywords: perturbations entangled; inflationary universe; scalar field; entangled pairs ... See more keywords
Cosmological perturbations with inverse-volume corrections in loop quantum cosmology
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DOI: 10.1103/physrevd.98.083507
Abstract: Although the cosmological perturbations with inverse-volume corrections from loop quantum cosmology have been studied using the anomaly-free algebra approach in much of the literature, there still remains an important issue that some counterterms in the… read more here.
Keywords: volume corrections; cosmology; inverse volume; cosmological perturbations ... See more keywords
Cosmological perturbations from full quantum gravity
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DOI: 10.1103/physrevd.98.106019
Abstract: The early universe provides an opportunity for quantum gravity to connect to observation by explaining the large-scale structure of the Universe. In the group field theory (GFT) approach, a macroscopic universe is described as a… read more here.
Keywords: quantum; perturbations full; geometry; quantum gravity ... See more keywords
Holographic dark energy from nonadditive entropy: Cosmological perturbations and observational constraints
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DOI: 10.1103/physrevd.99.103524
Abstract: We apply the holographic principle in the cosmological context through the nonextensive Tsallis entropy, used to describe the thermodynamic properties of nonstandard statistical systems such as the gravitational ones. Assuming the future event horizon as… read more here.
Keywords: holographic dark; entropy; dark energy; energy ... See more keywords