The Dark Dimension in a Warped Throat

Understand

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 $\ell\sim \Lambda^{-1/4}\sim 10^{-6}$m.
• We point out that a strongly warped throat with its redshifted KK tower provides a natural string theoretic mechanism that realizes the scaling $m\sim \Lambda^{\alpha}$ with the factor $\alpha=1/4$, 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.