On Towers of Light States at Infinite Distance

Upon investigating asymptotic regimes of the F-theory moduli space, we verify that a tower of light states arises as predicted by the Distance Conjecture. Specifically, we provide a geometric classification of the infinite distance limits and comprehensively analyze the light states of the associated effective theories. We thereby find for every infinite distance limit that the effective theory either reduces to a weakly-coupled (dual) string theory or decompactifies to a higher-dimensional theory. This is in full agreement with the Emergent String Conjecture, which clarifies the physical nature of the light particle tower either as the excitation modes of an emergent weakly-coupled string or as the Kaluza-Klein modes associated with a decompactification of the spacetime. The results reported encompass both the K\"ahler and the complex structure limits of F-theory, respectively, in $4$ and $8$ dimensions, and hence are indicative of the overarching microscopic origins of the light towers.