Higher-Group Symmetries and Weak Gravity Conjecture Mixing

TL;DR

This paper explores the relationship between higher-group symmetries and Weak Gravity Conjecture mixing in axion electrodynamics and supergravity, revealing a unified structure ensuring consistency across multiple dimensions.

Contribution

It demonstrates the connection between higher-group symmetries and Weak Gravity Conjecture mixing, extending the analysis to various supergravity theories in multiple dimensions.

Findings

Higher-group symmetries arise from Chern-Simons couplings in 4D axion electrodynamics.

Weak Gravity Conjecture mixing occurs between axion and gauge field charges.

The relationship extends to supergravities in 5 to 10 dimensions.

Abstract

In four-dimensional axion electrodynamics, a Chern-Simons coupling of the form $\theta F \wedge F$ leads to a higher-group global symmetry between background gauge fields. At the same time, such a Chern-Simons coupling leads to a mixing between the Weak Gravity Conjectures for the axion and the gauge field, so that the charged excitations of a Weak Gravity Conjecture-satisfying axion string will also satisfy the Weak Gravity Conjecture for the gauge field. In this paper, we argue that these higher-group symmetries and this phenomenon of Weak Gravity Conjecture mixing are related to one another. We show that this relationship extends to supergravities in 5, 6, 7, 8, 9, and 10 dimensions, so higher-dimensional supergravity is endowed with precisely the structure needed to ensure consistency with emergent higher-group symmetries and with the Weak Gravity Conjecture. We further argue that a similar mixing of Weak Gravity Conjectures can occur in two-term Chern-Simons theories or in theories with kinetic mixing, though the connection with higher-group symmetries here is more tenuous, and accordingly the constraints on effective field theory are not as sharp.