8d Supergravity, Reconstruction of Internal Geometry and the Swampland

TL;DR

This paper refines Swampland constraints on 8d supergravity by analyzing brane probe theories, reconstructing internal geometry, and identifying theories with G2 gauge symmetry as inconsistent with string theory principles.

Contribution

It introduces new consistency conditions from brane probes and a stronger cobordism conjecture to reconstruct internal geometry and restrict gauge algebras in 8d supergravity.

Findings

8d supergravity with G2 gauge symmetry are in the Swampland.

Reconstruction of internal geometry constrains gauge algebra and higher derivative terms.

Results support the string lamppost principle in 8d with 16 supercharges.

Abstract

We sharpen Swampland constraints on 8d supergravity theories by studying consistency conditions on worldvolume theory of 3-brane probes. Combined with a stronger form of the cobordism conjecture, this leads to the reconstruction of the compact internal geometry and implies strong restrictions on the gauge algebra and on some higher derivative terms (related to the level of the current algebra on the 1-brane). In particular we argue that 8d supergravity theories with $\mathfrak{g}_2$ gauge symmetry are in the Swampland. These results provide further evidence for the string lamppost principle in 8d with 16 supercharges.