Loop corrections and graceful exit in string cosmology

Foffa, Stefano; Maggiore, Michele; Sturani, R.

doi:10.1016/s0550-3213(99)00248-5

Cited by 54 publications

(63 citation statements)

References 63 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In string theory we have other non-perturbative and loop corrections such as the Gauss-Bonnet curvature invariant [31,32,36]. It is certainly of interest to extend our analysis to such a direction.…”

Section: Discussionmentioning

confidence: 99%

Dilatonic ghost condensate as dark energy

Piazza

Tsujikawa

2004

J. Cosmol. Astropart. Phys.

428

498

View full text Add to dashboard Cite

We explore a dark energy model with a ghost scalar field in the context of the runaway dilaton scenario in low-energy effective string theory. We address the problem of vacuum stability by implementing higher-order derivative terms and show that a cosmologically viable model of "phantomized" dark energy can be constructed without violating the stability of quantum fluctuations. We also analytically derive the condition under which cosmological scaling solutions exist starting from a general Lagrangian including the phantom type scalar field. We apply this method to the case where the dilaton is coupled to non-relativistic dark matter and find that the system tends to become quantum mechanically unstable when a constant coupling is always present. Nevertheless, it is possible to obtain a viable cosmological solution in which the energy density of the dilaton eventually approaches the present value of dark energy provided that the coupling rapidly grows during the transition to the scalar field dominated era.

show abstract

Section: Discussionmentioning

confidence: 99%

Dilatonic ghost condensate as dark energy

Piazza

Tsujikawa

2004

J. Cosmol. Astropart. Phys.

428

498

View full text Add to dashboard Cite

show abstract

“…Examples of regular backgrounds have recently been obtained by supplementing the low-energy effective action of string theory by the kind of higher-order corrections given in eq. (2) [12,13]. Fig.…”

Section: An Example: the Pre-big Bang Scenariomentioning

confidence: 97%

Evolution of cosmological perturbations in nonsingular string cosmologies

2001

View full text Add to dashboard Cite

In a class of non-singular cosmologies derived from higher-order corrections to the low-energy bosonic string action, we derive evolution equations for the most general cosmological scalar, vector and tensor perturbations. In the large scale limit, the evolutions of both scalar and tensor perturbations are characterised by conserved quantities, the usual curvature perturbation in the uniform-field gauge and the tensor-type perturbed metric. The vector perturbation is not affected, being described by the conservation of the angular momentum of the fluid component in the absence of any additional dissipative process. For the scalar-and tensor-type perturbations, we show how, given a background evolution during kinetic driven inflation of the dilaton field, we can obtain the final power spectra generated from the vacuum quantum fluctuations of the metric and the dilaton field during the inflation.PACS numbers: 98.80.Hw

show abstract

“…While K(φ) is positive at the tree level, it can change sign in the strongly coupled regime. In fact taking into account two-derivative perturbative loop corrections to the Kahler potential derived from heterotic string theory compactified on a Z N orbifold, the function ω(φ) is subject to change [31] ω(φ) = −e −φ 1 + 3 2…”

Section: Einstein Framementioning

confidence: 99%

Realizing scale-invariant density perturbations in low-energy effective string theory

2007

View full text Add to dashboard Cite

We discuss the realization of inflation and resulting cosmological perturbations in the low-energy effective string theory. In order to obtain nearly scale-invariant spectra of density perturbations and a suppressed tensor-to-scalar ratio, it is generally necessary that the dilaton field φ is effectively decoupled from gravity together with the existence of a slowly varying dilaton potential. We also study the effect of second-order corrections to the tree-level action which are the sum of a Gauss-Bonnet term coupled to φ and a kinetic term (∇φ) 4 . We find that it is possible to realize observationally supported spectra of scalar and tensor perturbations provided that the correction is dominated by the (∇φ) 4 term even in the absence of the dilaton potential. When the Gauss-Bonnet term is dominant, tensor perturbations exhibit violent negative instabilities on small-scales about a de Sitter background in spite of the fact that scale-invariant scalar perturbations can be achieved.

show abstract

Loop corrections and graceful exit in string cosmology

Cited by 54 publications

References 63 publications

Dilatonic ghost condensate as dark energy

Dilatonic ghost condensate as dark energy

Evolution of cosmological perturbations in nonsingular string cosmologies

Realizing scale-invariant density perturbations in low-energy effective string theory

Contact Info

Product

Resources

About