$AdS_6$ T-duals and Type IIB $AdS_6\times S^2$ Geometries with 7-Branes
Yolanda Lozano, Niall T. Macpherson, Jesús Montero
TL;DR
This work shows that the first Type IIB $AdS_6$ backgrounds obtained by Abelian and non-Abelian T-duality of the Brandhuber-Oz solution fit within an extended global DGKU/DGU framework of $AdS_6\times S^2\times\Sigma$ warped by a two-dimensional Riemann surface. The Abelian case maps to an annulus topology with smeared NS5 and D7/O7 branes, while the non-Abelian case corresponds to an infinite strip (upper half-plane) with smeared branes, enabling a consistent holographic interpretation via the DGKU/DGU data. Central charges and entanglement entropies are computed from the DGKU data, showing $N^{5/2}$ scaling for the Abelian case and an intervalwise $n^3$ growth for the non-Abelian case, consistent with a USp$(2N)$-like CFT structure and an infinite linear quiver that requires a completion. The paper also details the monodromy realization of 7-branes, the matching of fluxes, and the worldsheet mapping under non-Abelian T-duality, providing a framework to interpret these T-duals as holographic duals of 5d fixed-point theories with extended brane configurations.
Abstract
We show that the first $AdS_6$ backgrounds in Type IIB supergravity known in the literature, namely those constructed via T-duality from the Brandhuber-Oz solution to massive IIA, fit within an extension of the global $AdS_6 \times S^2$ solutions with 7-branes warped over a Riemann surface $Σ$, recently classified by D'Hoker, Gutperle and Uhlemann, that describes delocalised 5-branes and 7-branes. The solution constructed through Abelian T-duality provides an explicit example of a Riemann surface with the topology of an annulus, that includes D7/O7-branes. In turn, the solution generated through non-Abelian T-duality arises from the upper half-plane.
