Cosmological consequences of a time-dependent<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>Λ</mml:mi></mml:math>term

Carvalho, J. C.; Lima, J. A. S.; Waga, I.

doi:10.1103/physrevd.46.2404

Cited by 396 publications

(361 citation statements)

References 15 publications

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“…Since long ago, many different phenomenological decay laws for Λ(H) were proposed in the literature (see [1,2,3,4,5] for the oldest literature and [6,7,8,9] for more recent articles). The predictions of the latest models have also been confronted with the available observational data and the results compared with the predictions of the standard ΛCDM cosmology [10,11].…”

Section: Introductionmentioning

confidence: 99%

Primordial gravitational waves in running vacuum cosmologies

Tamayo

Lima

Alves

et al. 2017

Astroparticle Physics

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We investigate the cosmological production of gravitational waves in a nonsingular flat cosmology powered by a "running vacuum" energy density described by ρ Λ ≡ ρ Λ (H), a phenomenological expression potentially linked with the renormalization group approach in quantum field theory in curved spacetimes. The model can be interpreted as a particular case of the class recently discussed by Perico et al. (Phys. Rev. D 88, 063531, 2013) which is termed complete in the sense that the cosmic evolution occurs between two extreme de Sitter stages (early and late time de Sitter phases). The gravitational wave equation is derived and its time-dependent part numerically integrated since the primordial de Sitter stage. The generated spectrum of gravitons is also compared with the standard calculations where an abrupt transition, from the early de Sitter to the radiation phase, is usually assumed. It is found that the stochastic background of gravitons is very similar to the one predicted by the cosmic concordance model plus inflation except at higher frequencies (ν 100 kHz). This remarkable signature of a "running vacuum" cosmology combined with the proposed high frequency gravitational wave detectors and measurements of the CMB polarization (Bmodes) may provide a new window to confront more conventional models of inflation.

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Section: Introductionmentioning

confidence: 99%

Primordial gravitational waves in running vacuum cosmologies

Tamayo

Lima

Alves

et al. 2017

Astroparticle Physics

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“…As an alternative to the scalar field approach, it is also possible to introduce additional dynamics to the cosmological model by means of a phenomenological timedependent cosmological term Λ(t) [13][14][15][16][17][18] (see also [19] for a discussion of Λ(t) models arising in the context of QFT in curved space-time). In this scenario, the timedependent cosmological term yields a coupling with another cosmic component, which implies either particle production or an increase in the time-varying mass of the dark matter particles [20].…”

Section: Introductionmentioning

confidence: 99%

DBI analog of a decaying vacuum cosmology

Bessada

2013

Phys. Rev. D

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In this work I discuss the dynamical and thermodynamical equivalence between a general kessence scalar field cosmology and an arbitrary cosmological model with a decaying vacuum, thus generalizing the approach proposed by Maia and Lima [Phys. Rev. D 65, 083513 (2002)]. The formalism obtained is quite general and holds for any non-canonical scalar field model. As a special case I derive a Dirac-Born-Infeld (DBI) model with an exponential potential and constant speed of sound, and show that it is equivalent to a cosmological model with decay law Λ(H) = 3βH 2 .

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“…(12) that this model of gravity provides a braneworld scenario with a running effective cosmological "constant". As such this novel aspect is promising for cosmology as it can make feasible the emerging of interactions between dark energy and dark matter [17][18][19][20][21][22][23][24][25][26].…”

Section: Resultsmentioning

confidence: 99%

“…This equation carries an effective cosmological constant which now becomes a function of the coordinates due to the terms inherited from the modified gravity. This feature is attractive from the cosmological point of view, as a time-dependent cosmological "constant" makes possible a construction of a model of universe where the components of the dark sector are able to interact each other, exchanging energy and momentum [17][18][19][20][21][22][23][24][25][26]. This class of cosmologies usually comes into play as an attempt of addressing the socalled "coincidence problem" [27].…”

Section: Applying the Gauss-codazzi Formalismmentioning

confidence: 99%