714 research outputs found

### Supersymmetry and Wrapped Branes in Microstate Geometries

We consider the supergravity back-reaction of M2 branes wrapping around the
space-time cycles in 1/8-BPS microstate geometries. We show that such brane
wrappings will generically break all the supersymmetries. In particular, all
the supersymmetries will be broken if there are such wrapped branes but the net
charge of the wrapped branes is zero. We show that if M2 branes wrap a single
cycle, or if they wrap a several of co-linear cycles with the same orientation,
then the solution will be 1/16-BPS, having two supersymmetries. We comment on
how these results relate to using W-branes to understand the microstate
structure of 1/8-BPS black holes.Comment: 20 page

### BPS equations and Non-trivial Compactifications

We consider the problem of finding exact, eleven-dimensional, BPS
supergravity solutions in which the compactification involves a non-trivial
Calabi-Yau manifold, ${\cal Y}$, as opposed to simply a $T^6$. Since there are
no explicitly-known metrics on non-trivial, compact Calabi-Yau manifolds, we
use a non-compact "local model" and take the compactification manifold to be
${\cal Y} = {\cal M}_{GH} \times T^2$ where ${\cal M}_{GH}$ is a
hyper-K\"ahler, Gibbons-Hawking ALE space. We focus on backgrounds with three
electric charges in five dimensions and find exact families of solutions to the
BPS equations that have the same four supersymmetries as the three-charge black
hole. Our exact solution to the BPS system requires that the Calabi-Yau
manifold be fibered over the space-time using compensators on ${\cal Y}$. The
role of the compensators is to ensure smoothness of the eleven-dimensional
metric when the moduli of ${\cal Y}$ depend on the space-time. The Maxwell
field Ansatz also implicitly involves the compensators through the frames of
the fibration. We examine the equations of motion and discuss the brane
distributions on generic internal manifolds that do not have enough symmetry to
allow smearing.Comment: 32 pages, no figure

### Resolving the Structure of Black Holes: Philosophizing with a Hammer

We give a broad conceptual review of what we have learned about black holes
and their microstate structure from the study of microstate geometries and
their string theory limits. We draw upon general relativity, supergravity,
string theory and holographic field theory to extract universal ideas and
structural features that we expect to be important in resolving the information
problem and understanding the microstate structure of Schwarzschild and Kerr
black holes. In particular, we emphasize two conceptually and physically
distinct ideas, with different underlying energy scales: a) the transition that
supports the microstate structure and prevents the formation of a horizon and
b) the representation of the detailed microstate structure itself in terms of
fluctuations around the transitioned state. We also show that the supergravity
mechanism that supports microstate geometries becomes, in the string theory
limit, either brane polarization or the excitation of non-Abelian degrees of
freedom. We thus argue that if any mechanism for supporting structure at the
horizon scale is to be given substance within string theory then it must be
some manifestation of microstate geometries.Comment: 32 pages + reference

### Doubly-Fluctuating BPS Solutions in Six Dimensions

We analyze the BPS solutions of minimal supergravity coupled to an
anti-self-dual tensor multiplet in six dimensions and find solutions that
fluctuate non-trivially as a function of two variables. We consider families of
solutions coming from KKM monopoles fibered over Gibbons-Hawking metrics or,
equivalently, non-trivial T^2 fibrations over an R3 base. We find smooth
microstate geometries that depend upon many functions of one variable, but each
such function depends upon a different direction inside the T^2 so that the
complete solution depends non-trivially upon the whole T^2 . We comment on the
implications of our results for the construction of a general superstratum.Comment: 24 page

### Supersymmetric Janus Solutions in Four Dimensions

We use maximal gauged supergravity in four dimensions to construct the
gravity dual of a class of supersymmetric conformal interfaces in the theory on
the world-volume of multiple M2-branes. We study three classes of examples in
which the $(1+1)$-dimensional defects preserve $(4,4)$, $(0,2)$ or $(0,1)$
supersymmetry. Many of the solutions have the maximally supersymmetric $AdS_4$
vacuum dual to the $\mathcal{N}=8$ ABJM theory on both sides of the interface.
We also find new special classes of solutions including one that interpolates
between the maximally supersymmetric vacuum and a conformal fixed point with
$\mathcal{N}=1$ supersymmetry and $G_2$ global symmetry. We find another
solution that interpolates between two distinct conformal fixed points with
$\mathcal{N}=1$ supersymmetry and $G_2$ global symmetry. In eleven dimensions,
this $G_2$ to $G_2$ solution corresponds to a domain wall across which a
magnetic flux reverses orientation.Comment: 54 pages, 11 figure

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