The dark dimension in a warped throat

Abstract

By combining swampland conjectures with observational data, it was suggested that our universe should lie in an asymptotic region of the quantum gravity landscape. The generalized distance conjecture for dS, the smallness of the cosmological constant and astrophysical constraints led to a scenario with one mesoscopic large dimension of size ℓ∼Λ−1/4∼10−6 m. We point out that a strongly warped throat with its redshifted KK tower provides a natural string theoretic mechanism that realizes the scaling m∼Λα with the factor α=1/4, the dark dimension being the one along the throat. We point out that in string theory it could be challenging to keep other KK towers heavy enough to avoid a conflict with astrophysical constraints on the number of extra large dimensions.