Stabilization of extra dimensions at tree level

Watson, Scott; Brandenberger, Robert H.

doi:10.1088/1475-7516/2003/11/008

Cited by 104 publications

(184 citation statements)

References 13 publications

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“…As was discussed in [154,155] (see also earlier comments in [153]), the existence of string modes which are massless at the self-dual radius is crucial in obtaining radion stabilization in the Einstein frame (for more general studies of the importance of massless modes in string cosmology see [156,157]). Such massless modes do not exist in all known string theories.…”

Section: Moduli Stabilizationmentioning

confidence: 95%

Cosmology of the Very Early Universe

Brandenberger

Dupke²,

Alcaniz³

et al. 2010

AIP Conference Proceedings

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In these lectures I focus on early universe models which can explain the currently observed structure on large scales. I begin with a survey of inflationary cosmology, the current paradigm for understanding the origin of the universe as we observe it today. I will discuss some progress and problems in inflationary cosmology before moving on to a description of two alternative scenariosthe Matter Bounce and String Gas Cosmology. All early universe models connect to observations via the evolution of cosmological perturbations -a topic which will be discussed in detail in these lectures.

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Section: Moduli Stabilizationmentioning

confidence: 95%

Cosmology of the Very Early Universe

Brandenberger

Dupke²,

Alcaniz³

et al. 2010

AIP Conference Proceedings

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“…33 It has been proposed to use the string gas to stabilize internal dimensions as well as the dilaton [466][467][468][469][470], see also [471][472][473][474][475]. This proposal works within dilaton gravity and is not necessarily valid in the Hagedorn regime.…”

Section: A Preheating and Reheatingmentioning

confidence: 99%

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.

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“…To extract the fluctuation tensor of T µν for long wavelength modes, we take one additional variational derivative of (20), using (18) to obtain…”

Section: Energy-momentum Tensor Correlation Functions For Closed mentioning

confidence: 99%

“…For a mechanism to achieve the separation into three large and six small compact dimensions in the context of SGC see [1] (see however [12,13] for caveats), and for a natural dynamical mechanism arising from SGC to stabilize all of the moduli associated with the extra spatial dimensions see [18,19,20,21,22,23] (see also [24]). …”

Section: Introductionmentioning

confidence: 99%

String Gas Cosmology and Structure Formation

Brandenberger

Nayeri

Patil

et al. 2007

Int. J. Mod. Phys. A

138

172

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It has recently been shown that a Hagedorn phase of string gas cosmology may provide a causal mechanism for generating a nearly scale-invariant spectrum of scalar metric fluctuations, without the need for an intervening period of de Sitter expansion. A distinctive signature of this structure formation scenario would be a slight blue tilt of the spectrum of gravitational waves. In this paper we give more details of the computations leading to these results.

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Stabilization of extra dimensions at tree level

Abstract: By considering the effects of string winding and momentum modes on a time dependent background, we find a method by which six compact dimensions become stabilized naturally at the self-dual radius while three dimensions grow large.

Cited by 104 publications

References 13 publications

Cosmology of the Very Early Universe

Cosmology of the Very Early Universe

A critical review of classical bouncing cosmologies

String Gas Cosmology and Structure Formation

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