Dark energy, Ricci-nonflat spaces, and the swampland

Abstract

It was recently pointed out that the existence of dark energy imposes highly restrictive constraints on effective field theories that satisfy the Swampland conjectures. We provide a critical confrontation of these constraints with the cosmological framework emerging from the Salam-Sezgin model and its string realization by Cvetič, Gibbons, and Pope. We also discuss the implication of the constraints for string model building.