End of the World Boundaries for Chiral Quantum Gravity Theories

TL;DR

This paper constructs explicit string theory backgrounds with end of the world boundaries for 6d and 4d chiral theories, exploring strong coupling phenomena like phase transitions and symmetric mass generation.

Contribution

It introduces new classes of string backgrounds with end of the world boundaries for chiral theories, detailing their construction and associated strong coupling phenomena.

Findings

Constructed 6d and 4d chiral string backgrounds with boundaries.

Described strong coupling phenomena like phase transitions.

Linked constructions to chirality-changing phase transitions and geometric involutions.

Abstract

We describe the construction of large classes of explicit string theory backgrounds corresponding to 6d and 4d chiral theories with end of the world boundaries, and describe the strong coupling phenomena involved in gapping the chiral (but non-anomalous) sets of fields, such as strongly coupled phase transitions or symmetric mass generation. One class of 6d constructions is closely related to chirality changing phase transitions, such as those turning heterotic NS5-branes into gauge instantons, in flat space or orbifold singularities. A class of 4d models exploits systems of IIB D3-branes at toric CY3 singularities with an extra $\mathbf{Z}_2$ involution related to $G_2$ holonomy manifolds in the type IIB picture and its IIA mirror, which we explicitly describe in terms of dimer diagrams.