Mathematical Physics and Algebraic Geometry Seminar

Speaker: Rafael Álvarez García (Harvard University)

Title: (Strictly) Non-minimal Elliptic Threefolds and the Distance Conjecture

Abstract: We analyze infinite-distance limits in the complex structure moduli space of six-dimensional F-theory, providing an algebro-geometric classification and a physical interpretation. From the point of view of the Swampland Program, the motivation is to understand the fate of open-moduli infinite-distance limits in relation with the Distance Conjecture. From an F-theory perspective, the infinite-distance limits correspond to degenerations of elliptic threefolds leading to non-minimal singularities in codimension one and higher. We show how such non-crepant singularities can be removed by a systematic sequence of blow-ups of the bases of the infinite-distance degenerations, making their central fibers a union of log Calabi-Yau spaces glued together along their boundaries. We interpret said central fibers as either the endpoints of decompactification limits with six-dimensional defects or as emergent string limits, providing further evidence for the Emergent String Conjecture. Degenerations leading to strictly non-minimal singularities can correspond both to finite-distance and infinite-distance limits in the open moduli space. We analyze the chain of modifications and base changes necessary to unambiguously determine the fate of such families of F-theory models.