We find the holographic dual to the three classes of superconformal Janus interfaces in N = 4 SYM that preserve three-dimensional N = 4, N = 2, and N = 1 supersymmetry. The solutions are constructed in five-dimensional SO(6) maximal gauged supergravity and are then uplifted to type IIB supergravity. Corresponding to each of the three classes of Janus solutions, there are also AdS 4 × S 1 × S 5 J-fold backgrounds. These J-folds have a non-trivial SL(2, Z) monodromy for the axio-dilaton on the S 1 and are dual to three-dimensional superconformal field theories.

Double Field Theory suggests to view the whole massless sector of closed strings as the gravitational unity. The fundamental symmetries therein, including the O(D, D) covariance, can determine unambiguously how the Standard Model as well as a relativistic point particle should couple to the closed string massless sector. The theory also refines the notion of singularity. We consider the most general, spherically symmetric, asymptotically flat, static vacuum solution to D = 4 Double Field Theory, which contains three free parameters and consequently generalizes the Schwarzschild geometry. Analyzing the circular geodesic of a point particle in string frame, we obtain the orbital velocity as a function of R/(M ∞ G) which is the dimensionless radial variable normalized by mass. The rotation curve generically features a maximum and thus non-Keplerian over a finite range, while becoming asymptotically Keplerian at infinity, R/(M ∞ G) → ∞. The adoption of the string frame rather than Einstein frame is the consequence of the fundamental symmetry principle. Our result opens up a new scheme to solve the dark matter/energy problems by modifying General Relativity at 'short' range of R/(M ∞ G).

We show that for every Sasaki-Einstein manifold, M5, the AdS5 × M5 background of type IIB supergravity admits two universal deformations leading to supersymmetric AdS4 solutions. One class of solutions describes an AdS4 domain wall in AdS5 and is dual to a Janus configuration with N = 1 supersymmetry. The other class of backgrounds is of the form AdS4 × S 1 × M5 with a nontrivial SL(2, Z) monodromy for the IIB axio-dilaton along the S 1 . These AdS4 solutions are dual to three-dimensional N = 1 SCFTs. Using holography we express the S 3 free energy of these theories in terms of the conformal anomaly of the four-dimensional N = 1 SCFT arising from D3-branes on the Calabi-Yau cone over M5.

Employing uplift formulae, we uplift supersymmetric AdS 6 black holes from F (4) gauged supergravity to massive type IIA and type IIB supergravity. In massive type IIA supergravity, we obtain supersymmetric AdS 6 black holes asymptotic to the Brandhuber-Oz solution. In type IIB supergravity, we obtain supersymmetric AdS 6 black holes asymptotic to the non-Abelian T-dual of the Brandhuber-Oz solution.

We study the general requirement for supersymmetric AdS 6 solutions in type IIB supergravity. We employ the Killing spinor technique and study the differential and algebraic relations among various Killing spinor bilinears to find the canonical form of the solutions. Our result agrees precisely with the work of Apruzzi et. al.[1] which used the pure spinor technique. We also obtained the four-dimensional theory through the dimensional reduction of type IIB supergravity on AdS 6 . This effective action is essentially a nonlinear sigma model with five scalar fields parametrizing SL(3, R)/SO(2, 1), modified by a scalar potential and coupled to Einstein gravity in Euclidean signature. We argue that the scalar potential can be explained by a subgroup CSO(1,1,1) ⊂ SL(3, R) in a way analogous to gauged supergravity.