Related papers: Chronology protection and the stringy exclusion pr…
We present new SO(4)-invariant and non-supersymmetric instanton solutions for the conformally coupled m^2=-2 and massive m^2=+4 (pseudo)scalars arising from a consistent truncation of 11-dimensional supergravity over AdS_4 x S^7/Z_k when…
We consider a few ansatzs for the four and seven forms of 11-dimensional supergravity over AdS_4 x S^7/Z_k while try to keep the geometry unchanged. From the 4-form equations, we arrive at some massless scalars and pseudoscalars in the bulk…
A new family of maximal supergravities in four dimensions, involving gaugings of the trombone scaling symmetry, has been recently introduced. Using exceptional generalised geometry, we show some supergravities in this class to arise by…
We study AdS$_3\times \text{S}^2$ solutions in massive IIA that preserve small ${\cal N}=(4,0)$ 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…
In this paper we obtain supersymmetric brane-like configurations in the vacuum of N=4 gauged $SU(2)\times SU(2)$ supergravity theory in four spacetime dimensions. Almost all of these vacuum solutions preserve either half or one quarter of…
It is known from the work in \cite{Lu:2007bu} of Lu et. al. that the non-supersymmetric charged D3-brane (with anisotropies in time as well as one of the spatial directions of D3-brane) of type IIB string theory is characterized by five…
We study M/D-branes in a null-brane background. By taking a near horizon limit, one is left with cosmological models in the corresponding Poincar\'e patches. To deal with their usual horizons, we either extend these models to global AdS or…
We provide a string theory realisation of a two-parameter family of Type IIB supergravity solutions of the form ${\rm WAdS}_3 \times {\rm WS}^3 \times M_4$, as near-horizon geometries of supersymmetric backgrounds involving D1-D5 branes,…
We analyze the spectrum of perturbative closed strings on AdS3 x S3 x T4 with Ramond-Ramond flux using integrable methods. By solving the crossing equations we determine the massless and mixed-mass dressing factors of the worldsheet S…
We consider three dimensional conformal field theories living on a stack of N anti-M2 branes at the tip of eight-dimensional supersymmetric cones. The corresponding supergravity solution is obtained by changing sign to the four-form in the…
We study chronology protection in stationary, rotationally symmetric spacetimes in 2+1 dimensional gravity, focusing especially on the case of negative cosmological constant. We show that in such spacetimes closed timelike curves must…
We construct $\mathcal{N}=(2,2)$ supersymmetric AdS$_3$ solutions of type IIB supergravity, dual to twisted compactifications of 4d $\mathcal{N}=4$ super-Yang--Mills on Riemann surfaces. We consider both theories with a regular topological…
We study supersymmetric $AdS_5\times \Sigma$ solutions, for $\Sigma$ being a topological disk with non-trivial $U(1)$ holonomy at the boundary or "half-spindle", in seven-dimensional $N=2$ gauged supergravity coupled to three vector…
We obtain the supergravity solution which describes a bound state of D-string/anti-D-string pairs attached to different fixed planes of an orbifold, in type IIB string theory compactified on T^4/Z_2. For parameters at which the conformal…
We propose a class of ${\rm AdS}_3/{\rm CFT}_2$ dualities with $\mathcal{N}=(2,2)$ supersymmetry. These dualities relate string theory on ${\rm AdS}_3 \times ({\rm S}^3\times \mathbb{T}^4)/{\rm G}$ to marginal deformations of the symmetric…
It has been known for some time that the AdS/CFT correspondence predicts a limit on the number of single particle states propagating on the compact spherical component of the AdS-times-sphere geometry. The limit is called the stringy…
We reconsider supersymmetric five dimensional rotating charged black holes, and their description in terms of D-branes. By wrapping some of the branes on K3, we are able to explore the role of the enhancon mechanism in this system. We…
There has been considerable recent interest in type II string compactifications on AdS$_3\times$S$^3\times$M$_{4}$ due to both new progress in the AdS$_3$/CFT$_2$ correspondence and an independent search for new ${\cal N}=(4,0)$…
The geometry of spinning codimension-two branes in AdS spacetime is analyzed in three and higher dimensions. The construction of non-extremal solutions is based on identifications in the covering of AdS space by isometries that have fixed…
Coincident D3-branes placed at a conical singularity are related to string theory on $AdS_5\times X_5$, for a suitable five-dimensional Einstein manifold $X_5$. For the example of the conifold, which leads to $X_5=T^{1,1}=(SU(2)\times…