Comments on Non-Supersymmetric Orientifolds at Strong Coupling

TL;DR

The paper investigates the strong-coupling dynamics of non-supersymmetric but tachyon-free configurations of anti-Dp-branes on orientifold Op-planes in type II string theory, focusing on a single anti-brane on a negatively charged plane for p=2,3,4. It combines weak-coupling spectra with duality arguments (M-theory lifts and T-duality) to predict strong-coupling endpoints and phase transitions that nucleate additional anti-branes. Explicit strong-coupling pictures are proposed for O3-, O4-, and O2- cases, such as two anti-D3s on an O3+ at strong coupling and two anti-M5s or anti-M2s in corresponding M-theory embeddings, guided by flux quantization and anomaly considerations. These results provide a non-supersymmetric but tractable framework to study brane dynamics and potential holographic regimes in the large-N limit while highlighting the limitations of naive lifts in non-BPS contexts.

Abstract

We consider several properties of a set of anti-D$p$-branes in the presence of orientifold $p$-planes in type II theory. This system breaks all the supersymmetries of the theory, but is free of tachyons. In particular, we center on the case of a single anti-D$p$-brane stuck at a negatively charged orientifold $p$-plane, and study its strong coupling behaviour for $p=2,3,4$. Interestingly enough, as the coupling increases the system undergoes a phase transition where an additional antibrane is created. We conclude with some remarks on the limit of large number of antibranes on top of orientifold planes.