Stringy Bubbles Solve de Sitter Troubles

TL;DR

This paper proposes a string theory-based model involving bubble nucleation and cosmic branes that naturally produce a de Sitter universe with a small positive cosmological constant, addressing a key challenge in theoretical physics.

Contribution

It introduces a novel stringy construction using bubble nucleation and conifold resolutions to realize four-dimensional de Sitter solutions with desirable physical properties.

Findings

Demonstrates a stringy cosmic brane model that yields de Sitter spacetime.

Shows how conifold singularity resolutions can produce de Sitter solutions.

Provides a framework for localized gravity and matter in string theory contexts.

Abstract

Finding four-dimensional de Sitter spacetime solutions in string theory has been a vexing quest ever since the discovery of the accelerating expansion of the universe. Building on a recent analysis of bubble-nucleation in the decay of (false-vacuum) AdS backgrounds where the interfacing bubbles themselves exhibit a de Sitter geometry we show that this resonates strongly with a stringy cosmic brane construction that naturally provides for an exponential mass-hierarchy, and localization of both gravity and matter, in addition to an exponentially suppressed positive cosmological constant. Finally, we argue that these scenarios can be realized in terms of a generalization of a small resolution of a conifold singularity in the context of a (Lorentzian) Calabi-Yau 5-fold, where the isolated (Lorentzian) two complex dimensional Fano variety is a four-dimensional de Sitter spacetime.