We find the gravity solution corresponding to a large number of Neveu-Schwarz or D5-branes wrapped on a two sphere so that we have pure Nu = 1 super Yang-Mills in the IR. The supergravity solution is smooth, it shows confinement, and it breaks the U(1)(R) chiral symmetry in the appropriate way. When the gravity approximation is valid the masses of glueballs are comparable to the masses of Kaluza-Klein (KK) states on the 5-brane, but if we could quantize strings on this background it looks like we should be able to decouple the KK states.

In the first part of this paper we find supergravity solutions corresponding to branes on worldvolumes of the form R d × Σ where Σ is a Riemann surface. These theories arise when we wrap branes on holomorphic Riemann surfaces inside K3 or CY manifolds. In some cases the theory at low energies is a conformal field theory with two less dimensions. We find some non-singular supersymmetric compactifications of M-theory down to AdS 5 . We also propose a criterion for permissible singularities in supergravity solutions.In the second part of this paper, which can be read independently of the first, we show that there are no non-singular Randall-Sundrum or de-Sitter compactifications for large class of gravity theories.

We review the generalized Witten-Nester spinor stability argument for flat domain wall solutions of gravitational theories. Neither the field theory nor the solution need be supersymmetric. Nor is the space-time dimension restricted. We develop the non-trivial extension required for AdS-sliced domain walls and apply this to show that the recently proposed "Janus" solution of Type IIB supergravity is stable non-perturbatively for a broad class of deformations. Generalizations of this solution to arbitrary dimension and a simple curious linear dilaton solution of Type IIB supergravity are byproducts of this work.

Using AdS/CFT, we study the addition of an arbitrary number of backreacting flavors to the Klebanov-Witten theory, making many checks of consistency between our new Type IIB plus branes solution and expectations from field theory. We study generalizations of our method for adding flavors to all N = 1 SCFTs that can be realized on D3-branes at the tip of a Calabi-Yau cone. Also, general guidelines suitable for the addition of massive flavor branes are developed.

We study AdS 3 × S 2 solutions in massive IIA that preserve small N = (4, 0) supersymmetry in terms of an SU(2)-structure on the remaining internal space. We find two new classes of solutions that are warped products of the form AdS 3 ×S 2 ×M 4 ×R. For the first, M 4 =CY 2 and we find a generalisation a D4-D8 system involving possible additional branes. For the second, M 4 need only be Kahler, and we find a generalisation of the T-dual of solutions based on D3branes wrapping curves in the base of an elliptically fibered Calabi-Yau 3-fold. Within these classes we find many new locally compact solutions that are foliations of AdS 3 × S 2 × CY 2 over an interval, bounded by various D brane and O plane behaviours. We comment on how these local solutions may be used as the building blocks of infinite classes of global solutions glued together with defect branes. Utilising T-duality we find two new classes of AdS 3 × S 3 × M 4 solutions in IIB. The first backreacts D5s and KK monopoles on the D1-D5 near horizon. The second is a generalisation of the solutions based on D3-branes wrapping curves in the base of an elliptically fibered CY 3 that includes non trivial 3-form flux.

In this paper we discuss an infinite family of new solutions in massive Type IIA supergravity with AdS 3 ×S 2 factors, preserving N = (0, 4) SUSY. After studying geometrical aspects of the backgrounds we propose a duality with a precise family of quivers that flow to (0,4) fixed points at low energies. These quivers consist on two families of (4,4) linear quivers coupled by matter fields. We present various tests of our proposal.Dedicated to the memory of Steven S. Gubser. 1 ylozano@uniovi.es 2

In this paper we propose a linear quiver with gauge groups of increasing rank as field theory dual to the AdS 5 background constructed by Sfetsos and Thompson through non-Abelian T-duality. The formalism to study 4d N = 2 SUSY CFTs developed by Gaiotto and Maldacena is essential for our proposal. We point out an interesting relation between (Hopf) Abelian and non-Abelian T-dual backgrounds that allows to see both backgrounds as different limits of a solution constructed by Maldacena and Núñez. This suggests different completions of the long quiver describing the CFT dual to the nonAbelian T-dual background that match different observables.

In this paper we present new analytic solutions of pure Type IIB supergravity plus D7branes describing the addition of an arbitrary number of flavors to the Klebanov-Tseytlin and Klebanov-Strassler backgrounds. We provide a precise field theory dual and a detailed analysis of the duality cascade which describes its RG flow. Matchings of beta functions and anomalies between the field theory and the string setup are presented. We give an understanding of Seiberg duality as a large gauge transformation on the RR and NSNS potentials. We also analyze the UV behavior of the field theory, that as suggested by the string background can be associated with a duality wall.