Abstract
We find four-dimensional de Sitter compactifications of type IIA supergravity by directly solving the 10-dimensional equations of motion. In the simplest examples, the internal space has the topology of a circle times an Einstein manifold of negative curvature. An orientifold acts on the circle with two fixed loci, at which an O8_{-} and an O8_{+} plane sit. These orientifold planes are fully backreacted and localized. While the solutions are numerical, the charge and tension of the orientifold planes can be verified analytically. Our solutions have moduli at tree level and can be made parametrically weakly coupled and weakly curved. Their fate in string theory depends on quantum corrections.
Highlights
Modeling dark energy is a basic challenge for fundamental physics
Most of the de Sitter solutions to date make use of a fourdimensional effective theory to describe the physics of the vacuum
The orientifold is an exact solution of string theory whose local behavior is correctly reproduced in these constructions
Summary
Modeling dark energy is a basic challenge for fundamental physics. For theories of gravity based on extra dimensions it is notoriously difficult to obtain positive cosmological constant (or “de Sitter”) compactifications [1]. The most conservative and robust approach to address these concerns is to look for simple classical de Sitter solutions of the full 10-dimensional supergravity equations. The supergravity backreaction one should expect for O planes is known from flat-space solutions, but until recently few nontrivial compactifications including them were known.
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