Running decompactification, sliding towers, and the distance conjecture

Abstract

Abstract We study towers of light particles that appear in infinite-distance limits of moduli spaces of 9-dimensional $$ \mathcal{N} $$ N = 1 string theories, some of which notably feature decompactification limits with running string coupling. The lightest tower in such decompactification limits consists of the non-BPS Kaluza-Klein modes of Type I′ string theory, whose masses depend nontrivially on the moduli of the theory. We work out the moduli-dependence by explicit computation, finding that despite the running decompactification the Distance Conjecture remains satisfied with an exponential decay rate $$ \alpha \ge 1/\sqrt{d-2} $$ α ≥ 1 / d − 2 in accordance with the sharpened Distance Conjecture. The related sharpened Convex Hull Scalar Weak Gravity Conjecture also passes stringent tests. Our results non-trivially test the Emergent String Conjecture, while highlighting the important subtlety that decompactifcation can lead to a running solution rather than to a higher-dimensional vacuum.