Abstract
Constructing an explicit compactification yielding a metastable de Sitter (dS) vacuum in a UV consistent string theory is an incredibly difficult open problem. Motivated by this issue, as well as the conjecture that all non-supersymmetric AdS vacua must decay, we discuss the alternative possibility of realizing an effective four-dimensional dS cosmology on a codimension-one bubble wall separating two AdS5 vacua. The construction further elaborates on the scenario of arXiv:1807.01570, where the aforementioned cosmology arises due to a non-perturbative decay and is embedded in a five-dimensional bulk in a time dependent way. In this paper we discuss the relation between this scenario and the weak gravity conjecture and further develop the details of the four-dimensional cosmology. We provide a bulk interpretation for the dS temperature as the Unruh temperature experienced by an accelerated observer riding the bubble. A source of four-dimensional matter arises from a string cloud in the bulk, and we examine the consequences for the particle mass spectrum. Furthermore, we show how effective four-dimensional Einstein gravity on the bubble is obtained from the five-dimensional Gauss equation. We conclude by outlining some implications that this paradigm will have for holography, inflation, the standard model, and black holes.
Highlights
JHEP10(2019)164 the condition that the bubble forms through an instanton with finite Euclidean action guarantees that the induced cosmological constant on the brane is positive
We show that the temperature associated with the Rindler horizon of a uniformly accelerating observer in AdS5 is equal to the temperature associated to the cosmological horizon of the four-dimensional de Sitter (dS), providing a bulk interpretation of the dS temperature
We will show that an extension of the higher form weak gravity conjecture (WGC) [25] to codimension-one branes is equivalent to the charge-to-tension relationship required for AdS to be unstable to the nucleation of charged p-branes first derived by Brown and Teitelboim [17, 26]
Summary
The basis for [5] is the nucleation of a spherical bubble mediating the decay of a nonsupersymmetric AdS vacuum to an AdS vacuum with lower energy. We will show that an extension of the higher form WGC [25] to codimension-one branes is equivalent to the charge-to-tension relationship required for AdS (supported by flux) to be unstable to the nucleation of charged p-branes first derived by Brown and Teitelboim [17, 26]. This flat domain wall does not have a finite Euclidean action and cannot nucleate in a decay process, defining the boundary of stability These similarities with the WGC applied to higher codimension objects, together with the equivalence to the Brown-Teitelboim result suggests an explicit argument behind the reasoning of [8, 9]
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