Branes and Black Holes (A London Satellite Meeting)
Monday 28th May 2012 to Friday 1st June 2012
09:30 to 10:15  Registration  
10:15 to 11:00 
F Denef (Katholieke Universiteit Leuven) String glasses and beyond
I will review some recent work on complex, glassy systems in string theory and cosmology.


11:00 to 11:30  Morning Coffee  Great Hall Foyer  
11:30 to 12:15 
Microstate Geometries  what do they tell us about Black Holes?
Black hole microstate geometries exist in the same regime of parameters as a large classical black hole, but have no horizon. One can construct incrediblylarge families of such geometries, and argue that they have the right properties to describe some of the typical microstates of the black hole. I will review the construction and properties of microstate solutions for supersymmetric, extremal nonsupersymmetric and nonextremal black holes, and discuss what they teach us about black hole physics.


12:15 to 13:00  Lifshitz as a deformation of AdS  
13:00 to 14:00  Lunch  Terrace  
14:00 to 14:45 
S Murthy (Universiteit Utrecht) Some progress in computing exact black hole entropy using localization
I will report on some recent progress in computing the exact quantum entropy of supersymmetric black holes using localization techniques. After a brief review of recent developments, I will present new results on the derivation of the full solution manifold of the localization equations in N=2 supergravity. I will then discuss some clues that are emerging about the (ir)relevance of (non) Fterms to the quantum black hole entropy.


14:45 to 15:30 
J Manschot (Universität Bonn) Dbranes on elliptic CalabiYau manifolds
I'll discuss the quantum geometry of elliptically fibered CalabiYau threefolds. A holomorphic anomaly equation for the topological string free energy is proposed, which is iterative in the genus expansion as well as in the curve classes in the base. Tduality on the fibre implies that the topological string free energy also captures the BPSinvariants of D4branes wrapping the elliptic fibre and a class in the base. We verify this proposal by explicit computation of the BPS invariants of 3 D4branes on the rational elliptic surface.


15:30 to 16:00  Afternoon Tea  Great Hall Foyer  
16:00 to 16:45 
S Ross (University of Durham) Holography for asymptotically locally Lifshitz spacetimes
I will review the holographic description of field theories with an anisotropic scaling symmetry. I will explain how to define general boundary data for this correspondence, and discuss the asymptotic expansion (the analogue of the FeffermanGraham expansion) and the holographic renormalization for general boundary data. At the end of the talk, I will describe work in progress on alternative boundary conditions.


16:45 to 17:30 
Untwisting the NHEK with spectral flows
Schroedinger spacetimes geometrically realize the nonrelativistic conformal group, reason for which they have been proposed as holographic duals to strongly coupled nonrelativistic CFTs. On the other hand, it has been recently shown that black holes in threedimensional Schroedinger spacetimes exhibit a previously unknown Virasoro asymptotic symmetry, which is indicative of a full conformal symmetry. To uncover it, I will construct a FeffermanGrahamlike expansion for the relevant modes in asymptotically threedimensional Schroedinger spacetimes by mapping them to an auxiliary AdS(3) spacetime, and show that the renormalized onshell action for these modes is identical to the one for the gravity modes in the auxiliary AdS(3). The holographic stressenergy tensor one obtains by this procedure is symmetric, conserved and its trace yields the same conformal anomaly as in AdS(3).


18:00 to 19:00  Reception  Terrace 
09:30 to 10:15 
Bianchi Attractors: A Classification of Extremal Black Brane Geometries
Extremal black branes are of interest because they correspond to the ground states of field theories at finite charge density in gauge/gravity duality. The geometry of such a brane need not be translationally invariant in the spatial directions along which it extends. A less restrictive requirement is that of homogeneity, which still allows points along the spatial directions to be related to each other by symmetries. In the talk we will discuss new classes of homogeneous but anisotropic extremal black brane horizons, which could naturally arise in gauge/gravity dual pairs. In 4+1 dimensional spacetime, we will show that such homogeneous black brane solutions are classified by the Bianchi classification, which is well known in the study of cosmology, and fall into nine classes.


10:15 to 11:00 
Black hole monodromy
In this talk we will revisit the computation of greybody factors using a novel set of tools based on the monodromy technique. Our aim is to emphasize that the analytic properties of the black hole background play a crucial role in the scattering problem. In particular, acknowledging the existence of the inner horizon allows for exact expressions of the transmission and reflection coefficients without taking any low or high frequency approximation. More interestingly, this approach sheds light on the CFT interpretation of the BH entropy as a Cardy formula for a large class of black holes in 4D and 5D.


11:00 to 11:30  Morning Coffee  Great Hall Foyer  
11:30 to 12:15 
Supersymmetric field theories on curved manifolds and holography
I will discuss certain aspects of supersymmetric gauge theories on curved manifolds and how these interplay with holography in supersymmetric asympotically locally AdS geometries. In particular, I will present proposals for gravity duals of field theories on different squashed threespheres.


12:15 to 13:00 
J Hartong (University of Copenhagen) Lifshitz Holographic Renormalization from AdS
Lifshitz spacetimes with critical exponent z=2 can obtained by dimensional reduction of Schroedinger spacetimes with critical exponent z=0. The latter spacetimes are asymptotically AdS solutions of AdS gravity coupled to an axiondilaton system (or even just a massless scalar field). This basic observation is used to perform holographic renormalization for 4dimensional asymptotically locally Lifshitz spacetimes by dimensional reduction of the corresponding problem of holographic renormalization for
5dimensional asymptotically AdS spacetimes coupled to an axiondilaton system. In this setup the 4dimensional structure of the Lifshitz FeffermanGraham expansion and the structure of the counterterm action, including the scale anomaly, will be discussed.


13:00 to 14:00  Lunch  Terrace  
14:00 to 14:45 
T Takayanagi ([Yukawa Institute for Theoretical Physics]) Holographic Dual of BCFT
We propose a holographic dual of a conformal field theory defined on a manifold with boundaries, i.e. boundary conformal field theory (BCFT). This new holography successfully calculates the boundary entropy or gfunction in two dimensional BCFTs and it agrees with the finite part of the holographic entanglement entropy. Moreover, we can naturally derive a holographic gtheorem. We conjecture a higher dimensional analogue of gtheorem and give some evidences from both the gravity and field theory side. We also discuss the gravity dual with boundaries with arbitrary shape.


14:45 to 15:30 
S ElShowk (CEA/Saclay) The Resurgent Bootstrap and the 3D Ising Model
In recent years the conformal bootstrap has emerged as a surprisingly powerful tool to study CFTs in dimensions greater than two. In this talk I will explain how crossing symmetry of the fourpoint function of scalar operators can be used to extract very nontrivial constraints on the spectrum of a putative CFT in arbitrary spacetime dimension. Applying these techniques in D=3 we will find that the 3D Ising model lies at a special point in the space of CFTs. Moreover, we will show that constraints from conformal invariance can be used to significantly reduce the error in the known estimates for the dimensions of operators and suggest a method to generalize this to a compute the dimensions of
all operators in the theory. Time permitting, I will mention some more general applications of this technology, including holography.


15:30 to 15:45  Afternoon Tea  Great Hall Foyer  
15:45 to 16:30 
Octonionic black holes
I will display the generalisation of solutions describing bound states of interacting nonBPS extremal black holes to N=8 supergravity. I will explain in particular how gravitini N=2 multiplets vector fields and some hypermultiplets scalars are involved in a nontrivial manner in these solutions. For this purpose I will define `special coordinates' for the N=8 moduli which generalise naturally the special Kaehler coordinates. Then I will display some physical properties of these solutions, and in particular the existence of three by three interactions that are absent in the BPS solutions, and which are responsible for an extra contribution to the ADM angular momentum.


16:30 to 17:15 
Massive and higher spin string scattering off Dbrane boundstates
We study scattering amplitudes of higher spin closedstring states off Dbrane boundstates. For states in the first Regge trajectory we find remarkable simplifications both at tree level and at one loop. We discuss the high energy behavior in the Regge limit and comment on the validity of the eikonal approximation in this regime.


18:00 to 21:00  Banquet  Quaglino's 
09:30 to 10:15 
A Strominger (Harvard University) Progress in dS/CFT 

10:15 to 11:00 
G Dall'agata (Università degli Studi di Padova) Flow equations for Black Holes in (gauged) supergravity
We review the fake superpotential formalism for describing extremal black holes and discuss its possible extensions to the case of black holes in asymptotically AdS spacetimes.


11:00 to 11:30  Morning Coffee  Terrace  
11:30 to 12:15 
Black holes spitting out supertubes
We search for stable bound states of nonextremal rotating threecharge black holes in five dimensions (CveticYoum black holes) and supertubes. We do this by studying the potential of supertube probes in
the nonextremal black hole background and find that generically the marginally bound state of the supersymmetric limit becomes metastable and disappears with nonextremality (higher temperature). However near extremality there is a range of parameters allowing for stable bound states, which have lower energy than the supertubeblack hole merger. Angular momentum is crucial for this effect. We use this setup in the D1D5 decoupling limit to map a thermodynamic instability of the CFT (a new phase which is entropically dominant over the black hole phase) to a tunneling instability of the black hole towards the supertubeblack hole bound state. This generalizes the results of "Moulting Black Holes", which mapped an entropy enigma in the bulk to the dual CFT in a supersymmetric setup.


12:15 to 13:00 
Systematics of supersymmetric flows along the conifold
Working in N=4 gauged supergravity, we analyze the conditions for fivedimensional supersymmetric domain walls, which correspond to holographic RG flows. Applying our results to a class of consistent truncations of string theory, we obtain a general flow for SCFT deformations, as well as a new flow closely related to the resolved conifold. We also discuss a superpotential for the baryonic branch of the KlebanovStrassler solution.


13:00 to 13:45  Some thoughts on black hole microstates  
13:45 to 18:00  Free afternoon 
09:30 to 10:15 
B de Wit (Universiteit Utrecht) Deformations of special geometry; in search of the topological string
The possible relation between the effective action for N=2 supergravity with couplings proportional to the square of the Weyl tensor and the topological string partition function is explored. A number of systematic features is extracted with particular attention to the presence of nonholomorphic corrections.


10:15 to 11:00 
Brane and black hole supergravity horizons
Insights into the physics of gauge theories and strings have been gained by looking into the properties of the horizons of brane and black hole supergravity solutions. In this talk, I shall present a systematic exploration of the topology and geometry of such horizons utilizing the recent progress that has been made in the classification of supergravity backgrounds. The focus will be in heterotic, type II and Mhorizons.


11:00 to 11:30  Morning Coffee  Great Hall Foyer  
11:30 to 12:15 
Conformal Symmetry for General Black Holes
The boundary conditions of general black holes in asymptotically flat spacetimes can be modified such that a conformal symmetry emerges. The black holes with asymptotic geometry modified in this manner satisfy the equations of motion of minimal supergravity in one dimension more. Their symmetry suggests that a dual conformal field theory description exists that can account for the black hole entropy even in the case of black holes that are far from extremality.


12:15 to 13:00 
Subtracted Geometry From Harrison Transformations
We consider general four dimensional black holes in string theory and show that their subtracted geometry  which makes the hidden conformal symmetry manifest  can be obtained by applying
Harrison transformations on the black holes.


13:00 to 14:00  Lunch  Great Hall Foyer  
14:00 to 14:45 
Constructing generic nonextremal blackhole solutions of N=2, d=4,5 supergravities
I will review the general construction of nonextremal blackhole and blackbrane solutions of N=2,d=4 and d=5 supergravity coupled to vector multiplets, and their properties. I will describe the explicit solutions of a few models, their extremal (supersymmetric and nonsupersymmetric) limits, entropies, nonextremality functions etc. and a formalism that simplifies dramatically the search and construction of those solutions.


14:45 to 15:30 
A Bagchi (University of Edinburgh) Flat Space Holography as a limit of AdS/CFT
We construct flatspace holography as a limit of usual AdS/CFT concentrating on the 3d bulk/2d boundary example. The asymptotic group of symmetries at null infinity of flat spacetimes is the infinite dimensional BondiMetznerSachs (BMS) group. We show how this emerges in the flatspace limit of AdS symmetries. The flat limit also induces a contraction on the CFT which in 2d reduces to the Galilean Conformal Algebra (GCA), studied previously in the context of nonrelativistic systems. Quantum gravity in flat space would be described by the representations of the GCA. We comment on the relevant representations of the GCA and correlation functions. We also mention some intriguing results in ongoing work on the "flat" BTZ.


15:30 to 16:00  Afternoon Tea  Terrace  
16:00 to 16:45 
Universal properties and the first law of black hole inner mechanics
Recently, we showed by explicit computations that the product of all the horizon areas is independent of the mass, regardless of the topology of the horizons. The universal character of this relation holds for all known five dimensional asymptotically flat black rings, and for black strings. This gives further evidence for the crucial role that the thermodynamic properties at each horizon play in understanding the entropy at the microscopic level. To this end we proposed a 'first law' for the inner Cauchy horizons of black holes. The validity of this formula, which seems to be universal, was explicitly checked in all cases.


16:45 to 17:30 
S Ramgoolam (Queen Mary, University of London) Branes, permutations and oscillators
The group theory of permutations plays a central role in understanding the emergence of giant graviton branes from gaugeinvariant operators in the dual gauge theory. This holds for BPS operators as well as their nonBPS excitations. Young diagrams, SchurWeyl duality and double cosets are some of the concepts that are useful in analysing the action of the gaugetheory oneloop dilatation operator acting on brane excitations. The analysis leads to harmonic oscillator systems describing strings attached to the branes. The talk will be based primarily on http://arxiv.org/abs/1204.2153.

09:30 to 10:15 
R Emparan (Universitat de Barcelona) Black brane fluid flows
We study how the hydrodynamics of a black brane changes when we enclose it in a finite cylindrical cavity with Dirichlet boundary conditions. For neutral black branes, we see how the GregoryLaflamme instability switches off and study the critical point where the instability disappears. For black D3 branes, as the cavity radius decreases one obtains the sequence of descriptions "blackfolds > fluid/AdSgravity > membrane paradigm". We show that, to leading order above extremality, "sound comes from the throat".


10:15 to 11:00 
W Song (Harvard University) Comments on dipole theories
Dipole theories are interesting for many reasons. On the one hand, the background is deformed, and therefore is a simple example of nonAdS holography. On the other hand, the bulk spacetime can be obtained by a generalized spectra flow, and therefore many properties are inherited from AdS. Furthermore, dipole/CFT duality is closely related to Kerr/CFT correspondence. By studying dipole theory, we could learn some information about the CFT that is dual to Kerr. In this talk I will comment on dipole/CFT duality, and string sigma models on dipole backgrounds.


11:00 to 11:30  Morning Coffee  Terrace  
11:30 to 12:15 
Black holes, Hilbertspace networks, and quantum information transfer
A unitary resolution of the black hole information problem, or unitarity crisis, appears to require transfer of quantum information from black holes to their surroundings, in conflict with fieldtheory locality. One can both model and constrain such evolution. A possible general setting for such evolution, capturing some aspects of locality, is in a Hilbertspace network.


12:15 to 13:00 
Black hole instabilities and local Penrose inequalities
Various higherdimensional black holes have been shown to be unstable by studying linearized gravitational perturbations. This is often very complicated. I shall describe a simpler method for demonstrating instability. The idea is to construct initial data describing a small perturbation of the black hole and which violates an inequality analogous to the 4d Penrose inequality. I will describe recent work applying the method to nonuniform black strings.


13:00 to 14:00  Special lunch  Terrace 