Seminars

The superconformal indeces of 4d SCFTs count their BPS states and, holographically, give information on the microstates of the dual black holes. A possible approach to the exact computation of the index requires solving the so-called Bethe Ansatz equations (BAE). In this talk, I will introduce a rewriting of the BAE in terms of elliptic functions, focusing on the case with 16 supercharges. Such a rewriting permits 1) to quantitatively capture the conjectural relation of BAE with the Calogero-Moser integrable system (and the related continuous solutions) and 2) to rephrase the BAE in terms of configurations of lines on a plane intersecting an elliptic curve.

Supersymmetric field theories on curves spaces have recently attracted a
lot of interest in the context of localization and exact results in QFT. I
will discuss the existence of superconformal and supersymmetric theories
on certain Euclidean and Lorentzian manifolds, with a view towards
holographic applications. In particular, I will present the restrictions
upon the space-time geometry coming from supersymmetry. In the
superconformal case, I will show how the (possibly curved) space-time
arises as the boundary geometry of a gravity dual.

We will report on charged 4 dimensional black hole solutions in
ads space which are dressed by axionic fields. We will show how axions
regularise black hole RN type geometries by providing a stealth negative
curvature term in the black hole lapse function. Using this fact, we will
construct hairy versions of this charged black holes with planar horizons.
These, as we will see, generalise the MTZ hairy black holes with a
conformally coupled scalar. We will then examine thermodynamic competition
in between the hairy and bald black holes discussing possible relations to
the holographic superconductor paradigm.

More than thirty years after its inception, maximal D=4 supergravity continues
to be a fascinating theoretical edifice. Interesting open issues include the
possible finiteness of the ungauged version, the connection to the worldvolume
theory of M2-branes and its possible holographic applications in condensed
matter systems.
The first example of gauged maximal supergravity dates back to Cremmer and
Julia in 1979. There an SO(8) inside of the full duality group of the
theory was promoted to a local symmetry group. The theory with it's vacuum
structure was supposed to be unique. A few weeks ago it has been discovered
that this guess is indeed wrong. There is a whole class of SO(8) gauged N=8
supergravities. This seems to be true for many other types of gaugings
opening interesting new possibilities. I will briefly review the basic
ingredients necessary in order to construct the theory and explain these new
interesting findings.

Superconformal symmetry is the largest spacetime symmetry that one can impose on a field theory.
For the construction of many supergravity theories, especially those with matter couplings, it is useful to start with a superconformal invariant action, and then break symmetries to remain with super-Poincar?gravity. This method works also for the construction of higher-derivative actions. More speculative, it can also shed light on quantum aspects of supergravity.

I discuss new developments in the Higher-Spin/O(N)
Vector Model correspondence. In particular, I discuss
the role of bulk singleton fields in describing the
breaking of O(N) symmetry in the boundary by a novel
mechanism which seems to be unique to vector model
holography.

We review properties of multi-charged
rotating black holes in asymptotically
Minkowski (and anti-deSitter)
space-times, as solutions of maximally
supersymmetric compactifications of
String Theory. We focus on recent
progress in deriving the conformal
invariance and the microscopics of
general, asymptotically Minkowski
rotating black holes in four- and
five-dimensions.

Black holes, branes and other string and M-theory solitons exhibit horizons. The investigation of these horizons has yielded important results like the thermodynamics of black holes and AdS/CFT. I shall present the classification of horizon geometries in heterotic, IIB and 11-dimensional supergravities. I shall demonstrate that they admit novel geometries which recently have found applications in differential geometry.

Kounterterm regularization in AdS
gravity considers the addition of
boundary terms which is a given
polynomial in the extrinsic and
intrinsic curvatures. We provide an
explicit comparison between the
conserved charges derived from
Kounterterm method and the
Ashtekhar-Magnon-Das (conformal) mass
definition for asymptotically AdS
spacetimes.

I will discuss a new method to find vacua of maximal gauged supergravity and its application to M-theory reductions. I will show how to produce interesting Minkowski vacua with partial SUSY breaking using locally geometric compactifications and I will discuss new non-supersymmetric Anti-de Sitter vacua and possible applications in the context of the gauge/gravity correspondence.

We study static black brane solutions in
the context of N = 2 U(1) gauged
supergravity in four dimensions. Using
the formalism of first-order flow
equations, we construct novel extremal
black brane solutions including examples
of Nernst branes, i.e. extremal black
brane solutions with vanishing entropy
density. We also discuss a class of non-
extremal generalizations which is
captured by the first-order formalism.

I will present a new formulation of the
local c-map, which makes use of the real
formulation of special Kahler geometry
associated with N = 2 supergravity. As
an application I will explain how the
temporal version of the c-map can be
used as a solution generating technique,
and present some new results regarding
black hole solutions.