Supersymmetry without Supersymmetry

TL;DR

The authors demonstrate that supersymmetry in four-dimensional vacua derived from M-theory can be hidden in perturbative Type IIA string theory when the compactification manifold is a U(1) fibration, with missing superpartners arising as Dirichlet 0-branes. By examining concrete examples (round and squashed S7, M(3,2) spaces) they show that non-perturbative M-theory can preserve more SUSY than perturbative IIA, due to RR-charge-carrying states absent in perturbation theory. They analyze the AdS4 backgrounds, KK reductions, and flux quantization, highlighting how mass scales and coupling relations (e.g., λ4 ∼ 1/λ^2) couple to the presence of D0-branes. The work underscores that perturbative SUSY does not necessarily reflect the full non-perturbative symmetry structure of the theory, with potential implications for interpreting SUSY in realistic compactifications.

Abstract

We present four-dimensional M-theory vacua with N>0 supersymmetry which, from the perspective of perturbative Type IIA string theory, have N=0. Such vacua can appear when the compactifying 7-manifold is a U(1) fibration. The missing superpartners are Dirichlet 0-branes. Someone unable to detect Ramond-Ramond charge would thus conclude that these worlds have no unbroken supersymmetry. In particular, the gravitinos (and also some of the gauge bosons) are 0-branes not seen in perturbation theory but which curiously remain massless however weak the string coupling.