Oh, wait, O8 de Sitter may be unstable!

TL;DR

This paper investigates the stability of four-dimensional de Sitter vacua from massive Type IIA supergravity with O8 sources, revealing a tachyonic instability related to D8-branes' movement.

Contribution

It identifies a specific instability in de Sitter solutions involving O8 sources, clarifying the nature of the underlying brane configurations.

Findings

The solution with O8$_-$ and D8-branes exhibits a tachyonic instability.

The instability is due to D8-branes moving away from the O8$_-$ plane.

The paper discusses how to distinguish between different O8 source types.

Abstract

We analyze the stability of four-dimensional de Sitter vacua constructed by compactifying massive Type IIA supergravity in the presence of two O8 sources [1]. When embedded in String Theory the first source has a clear interpretation as an O8$_-$ plane, but the second one could correspond to either an O8$_+$ plane or to an O8$_-$ plane with 16 D8-branes on top. We find that this latter solution has a tachyonic instability, corresponding to the D8-branes moving away from the O8$_-$ plane. We comment on the possible ways of distinguishing between these sources.