The D4-D8 Brane System and Five Dimensional Fixed Points

TL;DR

Addresses the problem of understanding five-dimensional fixed points with $E_{N_f+1}$ global symmetry by constructing dual Type I' descriptions through the D4-D8 near-horizon geometry in massive Type IIA theory. The gravity dual is a warped $AD S_6\times S^4$ background yielding the six-dimensional $F(4)$ gauged supergravity upon reduction, and it encodes the $E_{N_f+1}$ symmetry enhancement at strong coupling. The analysis identifies the degrees of freedom scaling like $Q_4^{5/2}$ in the large-$Q_4$ regime and connects the operator spectrum to KK modes on the background, including Higgs-branch operators with dimension $3k/2$ and conserved currents in $E_{N_f+1}$. This holographic framework provides a concrete, geometric realization of the $5$d fixed points and clarifies the interplay between the Higgs/Coulomb branch structure and the global symmetry enhancement.

Abstract

We construct dual Type I' string descriptions to five dimensional supersymmetric fixed points with $E_{N_f+1}$ global symmetry. The background is obtained as the near horizon geometry of the D4-D8 brane system in massive Type IIA supergravity. We use the dual description to deduce some properties of the fixed points.