The Fall of Stringy de Sitter

TL;DR

The paper analyzes metastable de Sitter vacua in KKLT-type compactifications, focusing on decay channels beyond simple decompactification. It extends KPV NS5-brane instanton techniques to warped, compact GKP/KLLT settings, deriving corrected bubble tensions that include moduli-rolling and gravitational effects. Numerical explorations reveal a dense discretuum of dS minima across multi-throat geometries, while explicit decay-rate calculations show NS5-brane mediated decays can be exponentially faster than KKLT-like CDL decays, often terminating in dS, Minkowski, or Big Crunch inside the bubble. Despite these rapid channels in certain regions, all decay times remain far longer than the current age of the universe, underscoring the ongoing persistence of our vacuum amid a vast landscape of metastable states. The work highlights the importance of considering a broad set of decay pathways in the string-theory landscape and their implications for cosmology and the ultimate fate of the universe.

Abstract

Kachru, Kallosh, Linde, & Trivedi recently constructed a four-dimensional de Sitter compactification of IIB string theory, which they showed to be metastable in agreement with general arguments about de Sitter spacetimes in quantum gravity. In this paper, we describe how discrete flux choices lead to a closely-spaced set of vacua and explore various decay channels. We find that in many situations NS5-brane meditated decays which exchange NSNS 3-form flux for D3-branes are comparatively very fast.

Figures (5)

• Figure 1: The possible dS vacua with $V_0$ for given $M$ illustrate the density of states consistent with a discretuum.
• Figure 2: Top: In the KPV process, $p$$\overline{\textnormal{D3}}$-branes polarize into an NS5-brane wrapping an $S^2$ on the $A$ cycle. The NS5-brane then slides to the opposite pole, becoming $M-p$ D3-branes. Bottom: In the thin-wall limit, the NS5-brane is instead wraps the $A$ cycle at a particular Euclidean radius.
• Figure 3: Potential in throat 1 (Model 1)
• Figure 4: Potential in throat 2 (Model 1)
• Figure 5: The bubble minus background action as a function of the cosmological constants. The variables are $S=\kappa_4^4\tau^2 \Delta S$, $L=\Lambda_-/\kappa_4^4\tau^2$, and $dL=\Delta\Lambda/\kappa_4^4\tau^2$.