Nihat Sadik Deger

Matter coupled AdS3 supergravities and their black strings

Abstract We couple n copies of N =(2,0) scalar multiplets to a gauged N =(2,0) supergravity in 2+1 dimensions which admits AdS 3 as a vacuum. The scalar fields are charged under the gauged R-symmetry group U (1) and parametrize certain Kahler manifolds with compact or non-compact isometries. The radii of these manifolds are quantized in the compact case, but arbitrary otherwise. In the compact case, we find half-supersymmetry preserving and asymptotically Minkowskian black string solutions. For a particular value of the scalar manifold radius, the solution coincides with that of Horne and Horowitz found in the context of a string theory in 2+1 dimensions. In the non-compact case, we find half-supersymmetry preserving and asymptotically AdS 3 string solutions which have naked singularities. We also obtain two distinct AdS 3 supergravities coupled to n copies of N =(1,0) scalar multiplets either by the truncation of the (2,0) model or by a direct construction.

Supersymmetric warped AdS in extended topologically massive supergravity

We determine the most general form of off-shell N=(1,1) supergravity field configurations in three dimensions by requiring that at least one off-shell Killing spinor exists. We then impose the field equations of the topologically massive off-shell supergravity and find a class of solutions whose properties crucially depend on the norm of the auxiliary vector field. These are spacelike-squashed and timelike-stretched AdS3 for the spacelike and timelike norms, respectively. At the transition point where the norm vanishes, the solution is null warped AdS3. This occurs when the coefficient of the Lorentz–Chern–Simons term is related to the AdS radius by μl=2. We find that the spacelike-squashed AdS3 can be modded out by a suitable discrete subgroup of the isometry group, yielding an extremal black hole solution which avoids closed timelike curves.

Non-standard intersections of S-branes in D = 11 supergravity

We construct new intersecting S-brane solutions in 11-dimensional supergravity which do not have supersymmetric analogs. They are obtained by letting brane charges to be proportional to each other. Solutions fall into two categories with respect to whether there is a non-diagonal term to be cancelled in the field equations or not. In each case we show that they can be constructed by using a simple set of rules which is similar to the harmonic function rule of the usual static p-branes. Furthermore, we study an intersection where the Chern-Simons term makes a non-zero contribution to the field equations. We show that this configuration has a singularity like other S-branes.

Multi-spin giants

We examine spherical p-branes in AdS_m x S^n, that wrap an S^p in either AdS_m (p=m-2) or S^n (p=n-2). We first construct a two-spin giant solution expanding in S^n and has spins both in AdS_m and S^n. For (m,n)={(5,5),(4,7),(7,4)}, it is 1/2 supersymmetric, and it reduces to the single-spin giant graviton when the AdS spin vanishes. We study some of its basic properties such as instantons, non-commutativity, zero-modes, and the perturbative spectrum. All vibration modes have real and positive frequencies determined uniquely by the spacetime curvature, and evenly spaced. We next consider the (0+1)-dimensional sigma-models obtained by keeping generally time-dependent transverse coordinates, describing warped product of a breathing-mode and a point-particle on S^n or AdS_m x S^1. The BPS bounds show that the only spherical supersymmetric solutions are the single and the two-spin giants. Moreover, we integrate the sigma-model and separate the canonical variables. We quantize exactly the point-particle part of the motion, which in local coordinates gives Poschl-Teller type potentials, and calculate its contribution to the anomalous dimension.

Renormalization group flows from D = 3, N=2 matter coupled gauged supergravities

We study holographic RG flows of N = 2 matter coupled AdS3 supergravities which admit both compact and non-compact sigma manifolds. For the compact case the supersymmetric domain wall solution interpolates between a conformal IR region and flat spacetime and this corresponds to a deformation of the CFT by an irrelevant operator. When it is non-compact, the solution can be interpreted as a flow between an UV fixed point and a non-conformal(singular) IR region. This is an exact example of a deformation flow when the singularity is physical. We also find a non-supersymmetric deformation flow when the scalar potential has a second AdS vacua. The ratio of the central charges is rational for certain values of the size of the sigma model. Next, we analyze the spectrum of a massless scalar on our background by transforming the problem into Schrodinger form. The spectrum is continuous for the compact case, yet it can be both continuous (with or without mass gap) and discrete otherwise. Finally, 2-point functions are computed for two examples whose quantum mechanical potentials are of Calogero type.

A note on supergravity solutions for partially localized intersecting branes

Abstract Using the method developed by Cherkis and Hashimoto we construct partially localized D3⊥D5(2), D4⊥D4(2) and M5⊥M5(3) supergravity solutions where one of the harmonic functions is given in an integral form. This is a generalization of the already known near-horizon solutions. The method fails for certain intersections such as D1⊥D5(1) which is consistent with the previous no-go theorems. We point out some possible ways of bypassing these results.

On the supersymmetric solutions of D=3 half-maximal supergravities

Abstract We initiate a systematic study of the solutions of three-dimensional matter-coupled half-maximal ( N = 8 ) supergravities which admit a Killing spinor. To this end we analyze in detail the invariant tensors built from spinor bilinears, a technique originally developed and applied in higher dimensions. This reveals an intriguing interplay with the scalar target space geometry SO ( 8 , n ) / ( SO ( 8 ) × SO ( n ) ) . Another interesting feature of the three-dimensional case is the implementation of the duality between vector and scalar fields in this framework. For the ungauged theory with timelike Killing vector, we explicitly determine the scalar current and show that its integrability relation reduces to a covariant holomorphicity equation, for which we present a number of explicit solutions. For the case of a null Killing vector, we give the most general solution which is of pp-wave type.

AdS/CFT and Randall-Sundrum Model Without a Brane

We reformulate the Randall-Sundrum (RS) model on the compactified AdS by adding a term proportional to the area of the boundary to the usual gravity action with a negative cosmological constant and show that gravity can still be localized on the boundary without introducing singular brane sources. The boundary conditions now follow from the field equations, which are obtained by letting the induced metric vary on the boundary. This approach gives similar modes that are obtained in [1] and clarifies the complementarity of the RS and the AdS/CFT pictures. Normalizability of these modes is checked by an inner-product in the space of linearized perturbations. The same conclusions hold for a massless scalar field in the bulk.

Supersymmetric solutions of N = (2, 0) topologically massive supergravity

We first make a Killing spinor analysis for a general three-dimensional off-shell

A Note on Intersections of S-branes with p-branes

N=(2,0)