Supergravity inflation on the brane

Bento, M. C.; Bertolami, Orfeu; Sen, Anjan A.

doi:10.1103/physrevd.67.023504

Cited by 291 publications

(525 citation statements)

References 22 publications

(22 reference statements)

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“…(43) by performing a Taylor expansion around φ = 0. The potential of the tachyon field computed in the bosonic string field theory is given by [35,36] …”

Section: B Small-field Modelsmentioning

confidence: 99%

Constraints on braneworld inflation from CMB anisotropies

Tsujikawa¹,

Liddle²

2004

J. Cosmol. Astropart. Phys.

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We obtain observational constraints on Randall-Sundrum type II braneworld inflation using a compilation of data including WMAP, the 2dF and latest SDSS galaxy redshift surveys. We place constraints on three classes of inflation models (large-field, small-field and hybrid models) in the high-energy regime, which exhibit different behaviour compared to the low-energy case. The quartic potential is outside the 2σ observational contour bound for a number of e-folds less than 60, and steep inflation driven by an exponential potential is excluded because of its high tensor-to-scalar ratio. It is more difficult to strongly constrain small-field and hybrid models due to additional freedoms associated with the potentials, but we obtain upper bounds for the energy scale of inflation and the model parameters in certain cases. We also discuss possible ways to break the degeneracy of consistency relations and inflationary observables.

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“…(43) by performing a Taylor expansion around φ = 0. The potential of the tachyon field computed in the bosonic string field theory is given by [35,36] …”

Section: B Small-field Modelsmentioning

confidence: 99%

Constraints on braneworld inflation from CMB anisotropies

Tsujikawa¹,

Liddle²

2004

J. Cosmol. Astropart. Phys.

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“…The generalized Chaplygin gas (GCG) [1] is a recent proposal in order to explain the observed acceleration of the Universe [2,3]. It is an exotic fluid with negative pressure whose equation of state is given by…”

mentioning

confidence: 99%

Letter: Generalized Chaplygin Gas with α = 0 and the ΛC D M Cosmological Model

Fabris

Gonçalves

Ribeiro

2004

General Relativity and Gravitation

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The generalized Chaplygin gas model is characterized by the equation of state p = − A ρ α . It is generally stated that the case α = 0 is equivalent to a model with cosmological constant and dust (ΛCDM ). In this work we show that, if this is true for the background equations, this is not true for the perturbation equations. Hence, the mass spectrum predicted for both models may differ. The generalized Chaplygin gas (GCG) [1] is a recent proposal in order to explain the observed acceleration of the Universe [2,3]. It is an exotic fluid with negative pressure whose equation of state is given bywith 0 ≤ α ≤ 1. This exotic fluid has been considered as an alternative to quintessence [4] and to the cosmological constant [5], which are other serious candidates to explain the accelerated expansion of the Universe. Many observational constraints have been obtained for cosmological models based on the GCG. One interesting aspect of such exotic fluid is connected with a possible unification of dark matter and dark energy through a simple fluid described by the equation of state (1). Some authors (see, for example, reference [6]) claim that the comparison with observation indicates that α is peaked around zero. At same time, it is generally argued in the literature that the case α = 0 is equivalent to a ΛCDM model [7,8,6]. The aim of the present letter is to show that, if this is true for the background solutions, it is not true for the linearized equations. In this sense, in what concerns the type Ia supernovae data both models leads to the same results, as well as for the position of the acoustic peaks in spectrum of the anisotropy of the cosmic microwave background radiation. But we expect a disagreement concerning the predictions for the mass spectrum.The case α = 0 means that the pressure remains constant as the Universe expands and the density decreases. Since, for this case, p = −A, the equations of motion for an isotropic and homogeneous Universe described by the flat Friedmann-Robertson-Walker metric are:

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“…From this equivalence perspective, one might also one to have a look at generalized [22] and modified Chaplygin cosmologies [6]. The bad news is that 1 A larger class of potentials containing this particular one was considered in [16].…”

Section: Identification Arising From Geometrymentioning

confidence: 99%

“…2 Different flavors of Chaplygin cosmologies have gathered much attention due to the role they play as unified dark matter models [22,23].…”

Section: Identification Arising From Geometrymentioning

confidence: 99%

Quintessence as k-essence

2005

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Quintessence and k-essence have been proposed as candidates for the dark energy component of the universe that would be responsible of the currently observed accelerated expansion. In this Letter we investigate the degree of resemblance between those two theoretical setups, and find that every quintessence model can be viewed as a k-essence model generated by a kinetic linear function. In addition, we show the true effects of k-essence begin at second order in the expansion of the kinetic function in powers of the kinetic energy.

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Supergravity inflation on the brane

Cited by 291 publications

References 22 publications

Constraints on braneworld inflation from CMB anisotropies

Constraints on braneworld inflation from CMB anisotropies

Letter: Generalized Chaplygin Gas with α = 0 and the ΛC D M Cosmological Model

Quintessence as k-essence

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