How a four-dimensional de Sitter solution remains outside the swampland

TL;DR

This paper demonstrates that four-dimensional de Sitter solutions can exist in the string landscape when considering time-dependent fluxes and quantum corrections, challenging the swampland conjecture.

Contribution

It shows that under certain conditions, de Sitter solutions remain in the landscape, even with quantum effects and time-dependent fluxes, contrary to previous beliefs.

Findings

De Sitter solutions are possible with time-dependent fluxes and quantum corrections.

Time-independent de Sitter solutions lack simple effective field theory descriptions.

Such solutions satisfy no-go and swampland criteria, including trans-Planckian censorship.

Abstract

We argue that, in the presence of time-dependent fluxes and quantum corrections, four-dimensional de Sitter solutions should appear in the type IIB string landscape and not in the swampland. Our construction considers generic choices of local and non-local quantum terms and satisfies the no-go and the swampland criteria, the latter being recently upgraded using the trans-Planckian cosmic censorship. Interestingly, both time-independent Newton constant and moduli stabilization may be achieved in such backgrounds even in the presence of time-dependent fluxes and internal spaces. However, once the time-dependence is switched off, any four-dimensional solution with de Sitter isometries appears to have no simple effective field theory descriptions and is back in the swampland.