Supersymmetry breaking, brane dynamics and Swampland conjectures

TL;DR

This paper explores brane interactions in non-supersymmetric string models, analyzing static potentials and demonstrating that the Weak Gravity Conjecture holds through charge-to-tension ratio renormalization.

Contribution

It provides a detailed analysis of brane dynamics in non-supersymmetric models and shows the Weak Gravity Conjecture is satisfied without supersymmetry.

Findings

Qualitative agreement across different regimes despite lack of supersymmetry

Verification of the Weak Gravity Conjecture via charge-to-tension ratio renormalization

Rich and varied brane dynamics in tachyon-free non-supersymmetric models

Abstract

We investigate interactions between branes of various dimensions, both charged and uncharged, in three non-supersymmetric string models. These include the $USp(32)$ and $U(32)$ orientifold projections of the type IIB and type $0$B strings, as well as the $SO(16) \times SO(16)$ projection of the exceptional heterotic string. The resulting ten-dimensional spectra are free of tachyons, and the combinations of branes that they contain give rise to rich and varied dynamics. We compute static potentials for parallel stacks of branes in three complementary regimes: the probe regime, in which one of the two stacks is parametrically heavier than the other, the string-amplitude regime, in which both stacks are light, and the holographic regime. Whenever comparisons are possible, we find qualitative agreement despite the absence of supersymmetry. For charged branes, our analysis reveals that the Weak Gravity Conjecture is satisfied in a novel way via a renormalization of the effective charge-to-tension ratio.