Intricacies of classical de Sitter string backgrounds

Up-to-date, there is no known example of a classical de Sitter solution of string theory, despite several good candidates. We consider here two newly discovered 10d supergravity de Sitter solutions, and analyse in great detail whether they can be promoted to classical string backgrounds. To that end, we identify five requirements to be met, and develop the necessary 10d tools to test the solutions. Eventually, they both fail to verify simultaneously all requirements, in spite of positive partial results. The explicit values obtained offer a clear illustration of the situation, and the analysis highlights various subtleties. We finally discuss the relation to the problem of scale separation. (C) 2020 The Authors. Published by Elsevier B.V.

Automated summary

This article discusses two newly discovered 10-dimensional supergravity de Sitter solutions and analyzes whether they can be promoted to classical string backgrounds. Despite some positive partial results, both solutions ultimately fail to simultaneously fulfill all requirements. The analysis emphasizes various subtleties and discusses the relation to the problem of scale separation.