(A)dS Backgrounds from Asymmetric Orientifolds

TL;DR

This paper constructs new AdS and de Sitter string backgrounds using asymmetric orientifolds with RR fluxes, achieving stabilized moduli and weak string coupling, advancing string cosmology models.

Contribution

Introduces asymmetric orientifold models with RR fluxes that stabilize all NS NS moduli, including the dilaton, leading to new AdS and promising de Sitter backgrounds.

Findings

Achieves fixed NS NS moduli and dilaton in string models.

Constructs AdS backgrounds with tunable weak string coupling.

Proposes metastable de Sitter backgrounds with moderate string coupling.

Abstract

I present asymmetric orientifold models which, with the addition of RR fluxes, fix all the NS NS moduli including the dilaton. In critical string theory, this gives new AdS backgrounds with (discretely tunably) weak string coupling. Extrapolating to super-critical string theory, this construction leads to a promising candidate for a metastable de Sitter background with string coupling of order 1/10 and dS radius of order 100 times the string scale. Extrapolating further to larger and larger super-critical dimension suggests the possibility of finding de Sitter backgrounds with weaker and weaker string coupling. This note is an updated version of the last part of my Strings 2001 talk.