相关论文: Proof of absence of de Sitter vacua in classical t…
We revisit the classical theory of ten-dimensional two-derivative gravity coupled to fluxes, scalar fields, D-branes, anti D-branes and Orientifold-planes. We show that such set-ups do not give rise to a four-dimensional positive curvature…
We derive highly constraining no-go theorems for classical de Sitter backgrounds of string theory, with parallel sources; this should impact the embedding of cosmological models. We study ten-dimensional vacua of type II supergravities with…
We continue the study of compactifications of massive IIA supergravity on G2 orientifolds and demonstrate that breaking supersymmetry with anti-D2 and anti-D6 sources leads to 3d theories for which the typical tachyons haunting classical dS…
We argue that the heterotic string does not have classical vacua corresponding to de Sitter space-times of dimension four or higher. The same conclusion applies to type II vacua in the absence of RR fluxes. Our argument extends prior…
The classical-dS scenario in the type II string theories proposes to search for dS vacua of orientifold flux compactifications in a regime where string corrections to the compactified effective field theory are negligible. We study a…
We present further no-go theorems for classical de Sitter vacua in Type II string theory, i.e., de Sitter constructions that do not invoke non-perturbative effects or explicit supersymmetry breaking localized sources. By analyzing the…
We find four-dimensional de Sitter compactifications of type IIA supergravity by directly solving the ten-dimensional equations of motion. In the simplest examples, the internal space has the topology of a circle times an Einstein manifold…
We derive necessary criteria for the existence of classical, meta-stable, de Sitter solutions in flux compactifications of type II supergravity down to dimensions higher than four. We find that the possibilities in higher dimensions are…
In this paper we consider type IIA compactifications in the isotropic Z2 x Z2 orbifold with a flux-induced perturbative superpotential combined with non-perturbative effects. Without requiring the presence of O-planes, and simply having…
In this note we study a massive IIA supergravity theory obtained in hep-th/9707139 by compactification of M-theory. We point out that de Sitter space in arbitrary dimensions arises naturally as the vacuum of this theory. This explicitly…
We review the prospect of obtaining tree-level de Sitter (dS) vacua and slow-roll inflation models in string compactifications. Restricting ourselves to the closed string sector and assuming the absence of NSNS-sources, we classify the…
We construct compactifications of type IIB string theory that yield, at leading order in the $\alpha^\prime$ and $g_s$ expansions, de Sitter vacua of the form envisioned by Kachru, Kallosh, Linde, and Trivedi. We specify explicit Calabi-Yau…
We study cosmological properties of type IIA compactifications on orientifolds of SU(3)-structure manifolds with non-vanishing geometric flux. These compactifications give rise to effective 4D N=1 supergravity theories that do not fall…
Motivated by the connection of string theory to cosmology or particle physics, we study solutions of type II supergravities having a four-dimensional de Sitter or Minkowski space-time, with intersecting Dp-branes and orientifold Op-planes.…
We revisit the possibility of de Sitter vacua and slow-roll inflation in type II string theory at the level of the classical two-derivative supergravity approximation. Previous attempts at explicit constructions were plagued by ubiquitous…
We study M-theory compactification on ${\mathbb{T}^7/ \mathbb{Z}_2^3}$ in the presence of a seven-flux, metric fluxes and KK monopoles. The effective four-dimensional supergravity has seven chiral multiplets whose couplings are specified by…
We explore in detail the prospects of obtaining a four-dimensional de Sitter universe in classical supergravity models with warped and time-independent extra dimensions, presenting explicit cosmological solutions of the $(4+n)$-dimensional…
We study the existence and stability of classical de Sitter solutions of type II supergravities with parallel Dp-branes and orientifold Op-planes. Together with the dilaton and volume scalar fields, we consider a third one that…
We present stable de Sitter solutions of $\mathcal{N} = 1$ supergravity in a geometric type IIB duality frame with the addition of non-perturbative contributions. Contrary to the standard approach, we retain the moduli dependence of both…
We construct a new class of metastable de Sitter vacua of flux compactifications of type IIB string theory. These solutions provide a natural extension of the `Large Volume Scenario' anti-de Sitter vacua, and can analogously be realised at…