Dirac-Born-Infeld Genesis: An Improved Violation of the Null Energy Condition

Hinterbichler, Kurt; Joyce, Austin; Khoury, Justin; Miller, Godfrey E. J.

doi:10.1103/physrevlett.110.241303

Cited by 80 publications

(127 citation statements)

References 39 publications

(62 reference statements)

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“…The L I are Lovelock invariants and guarantee second order differential equations [233]. Suitable choices of the free coefficients, c I 's, allow for a solution e φ ∝ 1/t, leading to the stable violation of the NEC [358]. A nice feature of this model is that the speed of sound of fluctuations is subluminal while preserving conformal invariance; further, the solution is stable against radiative corrections and a stable Poincaré-invariant vacuum is present.…”

Section: • Ghost Fieldsmentioning

confidence: 99%

“…Desirable properties for a healthy bounce according to [358,359] Many proposed bouncing models have problems satisfying these conditions, as shown in table III taken from [359] for a limited selection of models, highlighting the improvements of some iterations within the framework of galileon theories. [359] provides an extended review of what is presented here.…”

Section: Nec Violationmentioning

confidence: 99%

“…To improve upon this shortcoming, even more complicated galileon theories have been considered, while still avoiding superluminality. An example is to consider Dirac-Born-Infeld (DBI) conformal galileons [358], as summarized in [359], which we follow below. These theories describe the motion of a 3-brane by means of an effective scalar field φ in an AdS 5 geometry.…”

Section: • Ghost Fieldsmentioning

confidence: 99%

“…These theories describe the motion of a 3-brane by means of an effective scalar field φ in an AdS 5 geometry. The resulting 4D Lagrangian for φ is given by [358] …”

Section: • Ghost Fieldsmentioning

confidence: 99%

“…See [355] for a recent review. Ghosts can be avoided in certain set-ups by employing, for example, a ghost condensate (higher derivatives) [356,357], conformal galileons [230] (conformally invariant scalar field theories with particular higher-derivative interactions) [238] or DBI conformal galileons (a 3-brane moving in an anti-de Sitter bulk, AdS 5 ), used, for example, in the inflationary models of DBI Genesis [358].…”

Section: Nec Violationmentioning

confidence: 99%

See 4 more Smart Citations

A critical review of classical bouncing cosmologies

2015

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Given the proliferation of bouncing models in recent years, we gather and critically assess these proposals in a comprehensive review. The PLANCK data shows an unmistakably red, quasi scaleinvariant, purely adiabatic primordial power spectrum and no primary non-Gaussianities. While these observations are consistent with inflationary predictions, bouncing cosmologies aspire to provide an alternative framework to explain them. Such models face many problems, both of the purely theoretical kind, such as the necessity of violating the NEC and instabilities, and at the cosmological application level, as exemplified by the possible presence of shear. We provide a pedagogical introduction to these problems and also assess the fitness of different proposals with respect to the data. For example, many models predict a slightly blue spectrum and must be fine-tuned to generate a red spectral index; as a side effect, large non-Gaussianities often result.We highlight several promising attempts to violate the NEC without introducing dangerous instabilities at the classical and/or quantum level. If primordial gravitational waves are observed, certain bouncing cosmologies, such as the cyclic scenario, are in trouble, while others remain valid. We conclude that, while most bouncing cosmologies are far from providing an alternative to the inflationary paradigm, a handful of interesting proposals have surfaced, which warrant further research. The constraints and lessons learned as laid out in this review might guide future research.

show abstract

Section: • Ghost Fieldsmentioning

confidence: 99%

Section: Nec Violationmentioning

confidence: 99%

Section: • Ghost Fieldsmentioning

confidence: 99%

“…These theories describe the motion of a 3-brane by means of an effective scalar field φ in an AdS 5 geometry. The resulting 4D Lagrangian for φ is given by [358] …”

Section: • Ghost Fieldsmentioning

confidence: 99%

Section: Nec Violationmentioning

confidence: 99%

See 3 more Smart Citations

A critical review of classical bouncing cosmologies

2015

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Scalars with Higher Derivatives in Supergravity and Cosmology

Lehners

2014

Breaking of Supersymmetry and Ultraviolet Divergences in Extended Supergravity

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The Effective Field Theory of nonsingular cosmology

Cai

Wan

et al. 2017

J. High Energ. Phys.

136

150

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In this paper, we explore the nonsingular cosmology within the framework of the Effective Field Theory (EFT) of cosmological perturbations. Due to the recently proved no-go theorem, any nonsingular cosmological models based on the cubic Galileon suffer from pathologies. We show how the EFT could help us clarify the origin of the no-go theorem, and offer us solutions to break the no-go. Particularly, we point out that the gradient instability can be removed by using some spatial derivative operators in EFT. Based on the EFT description, we obtain a realistic healthy nonsingular cosmological model, and show the perturbation spectrum can be consistent with the observations.

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Dirac-Born-Infeld Genesis: An Improved Violation of the Null Energy Condition

Cited by 80 publications

References 39 publications

A critical review of classical bouncing cosmologies

A critical review of classical bouncing cosmologies

Scalars with Higher Derivatives in Supergravity and Cosmology

The Effective Field Theory of nonsingular cosmology

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