Swampland Conjectures for Strings and Membranes

TL;DR

This paper explores how Swampland criteria extend to strings and membranes in 4d EFTs, revealing new relations among conjectures through their backreaction and RG flow interpretations.

Contribution

It introduces a framework connecting the backreaction of strings and membranes to RG flows, linking Swampland Conjectures via physical properties of low-codimension objects.

Findings

String RG flows correspond to infinite field distance limits.

WGC for strings implies the Swampland Distance Conjecture.

Membranes saturating WGC generate potentials satisfying the de Sitter Conjecture.

Abstract

Swampland criteria like the Weak Gravity Conjecture should not only apply to particles, but also to other lower-codimension charged objects in 4d EFTs like strings and membranes. However, the description of the latter is in general subtle due to their large backreaction effects. In the context of 4d $\mathcal{N}=1$ EFTs, we consider $\frac12$BPS strings and membranes which are fundamental, in the sense that they cannot be resolved within the EFT regime. We argue that, if interpreted from the EFT viewpoint, the 4d backreaction of these objects translates into a classical RG flow of their couplings. Constraints on the UV charges and tensions get then translated to constraints on the axionic kinetic terms and scalar potential of the EFT. This uncovers new relations among the Swampland Conjectures, which become interconnected by the physical properties of low-codimension objects. In particular, using that string RG flows describe infinite field distance limits, we show that the WGC for strings implies the Swampland Distance Conjecture. Similarly, WGC-saturating membranes generate a scalar potential satisfying the de Sitter Conjecture.