Accelerating cosmologies from M/String theory compactifications

Roy, Shibaji

doi:10.1016/j.physletb.2003.06.060

Cited by 109 publications

(76 citation statements)

References 31 publications

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“…We save these topics for future study. For large (cosmic) time t, we take the ansatz 6) for n > 0. The idea is that the two equations of motion scale differently for large t.…”

Section: Resultsmentioning

confidence: 99%

Hyperbolic space cosmologies

Chen

Neupane

et al. 2003

J. High Energy Phys.

112

113

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We present a systematic study of accelerating cosmologies obtained from M/string theory compactifications of hyperbolic spaces with time-varying volume. A set of vacuum solutions where the internal space is a product of hyperbolic manifolds is found to give qualitatively the same accelerating four-dimensional FLRW universe behavior as a single hyperbolic space. We also examine the possibility that our universe is a hyperbolic space and provide exact Milne type solutions, as well as intersecting S-brane solutions. When both the usual 4D spacetime and the m-dimensional internal space are hyperbolic, we find eternally accelerating cosmologies for m ≥ 7, with and without form field backgrounds. In particular, the effective potential for a magnetic field background in the large 3 dimensions is positive definite with a local minimum and thus enhances the eternally accelerating expansion.

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“…We save these topics for future study. For large (cosmic) time t, we take the ansatz 6) for n > 0. The idea is that the two equations of motion scale differently for large t.…”

Section: Resultsmentioning

confidence: 99%

Hyperbolic space cosmologies

Chen

Neupane

et al. 2003

J. High Energy Phys.

112

113

View full text Add to dashboard Cite

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“…For the heterotic strings, the leading correction is given by the GB terms with the coefficient [13,14]: 9) multiplied by an exponential factor of the dilaton, where α ′ is the Regge slope parameter.…”

Section: )mentioning

confidence: 99%

Inflation from superstring and M-theory compactification with higher order corrections

2005

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We study time-dependent solutions in M and superstring theories with higher order corrections. We first present general field equations for theories of Lovelock type with stringy corrections in arbitrary dimensions. We then exhaust all exact and asymptotic solutions of exponential and power-law expansions in the theory with Gauss-Bonnet terms relevant to heterotic strings and in the theories with quartic corrections corresponding to the M-theory and type II superstrings. We discuss interesting inflationary solutions that can generate enough e-foldings in the early universe.

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“…Astronomical observations indicate that our universe is flat and currently consists of approximately 2 3 dark energy and 1 3 dark matter. The nature of dark energy as well as dark matter is unknown, and many radically different models have been proposed, such as, a tiny positive cosmologi-cal constant, quintessence [16][17][18], DGP branes [19,20], the non-linear F(R) models [21][22][23], and dark energy in brane worlds, among many others [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43]; see also the review articles [44,45], and references therein. As mentioned before, the existence of dark energy fluids comes from the observations of the accelerated expansion of the universe and the isotropic pressure cosmological models give the best fitting of the observations.…”

Section: Introductionmentioning

confidence: 99%