# No classical (anti-)de Sitter solutions with O8-planes

## TL;DR

This paper proves that classical de Sitter solutions with O8-planes in type IIA string theory are impossible due to supergravity constraints, and also refutes some proposed non-supersymmetric AdS solutions involving O8-planes.

## Contribution

It establishes a no-go theorem ruling out classical de Sitter solutions with O8-planes and challenges recent non-supersymmetric AdS solutions claiming to include O8-planes.

## Key findings

- No classical de Sitter solutions with O8-planes exist.
- Certain non-supersymmetric AdS solutions with O8-planes are incompatible with supergravity equations.
- Divergences at O8-plane locations do not invalidate the no-go argument.

## Abstract

It was recently proposed that type IIA string theory may allow classical de Sitter solutions with O8-planes as the only localized sources. We show that such solutions are incompatible with the integrated supergravity equations of motion, analogously to the no-go theorem due to Maldacena and Nu\~{n}ez. We also discuss in detail divergences and discontinuities at the O8-plane positions and argue that they do not invalidate such an argument. We furthermore show that a recently proposed class of non-supersymmetric AdS solutions with O8-planes is in contrast with our results as well.