Speaker
Description
In this talk, I will discuss the realization of the Emergent String Conjecture in the vector multiplet moduli space of Type IIB compactifications on Calabi-Yau threefolds. Based on the classification of infinite distance limits in the complex structure moduli space of Calabi-Yau threefolds in terms of limiting mixed Hodge structures, such limits are expected to correspond to so-called type II_b limits for which b<h^{2,1} an integer. However, neither a tower of light BPS states nor a tensionless, critical string has been so far identified for general such limits. For the special class of type II_b limits realized as Tyurin degenerations of CY threefolds, I will use the additional information encoded in the geometry of the degenerate threefold to establish the existence of a tower of light BPS states and study the worldsheet theory on a geometric string solution which becomes tensionless at the same rate as the tower of BPS states in the type II_b limit. As a result, I will show that this tensionless string corresponds to a critical heterotic string with a perturbative gauge group of rank 2+b — consistent with the Emergent String Conjecture. Finally, by reversing the logic, I will discuss how the Emergent String Conjecture yields a new constraint on the type II_b limiting Hodge structures that can have a geometric realization on Calabi-Yau threefolds. This talk is based on joint work with Björn Friedrich, Jeroen Monnee, and Timo Weigand.
