3,942 research outputs found
Supersymmetric AdS_4 black holes and attractors
Using the general recipe given in arXiv:0804.0009, where all timelike
supersymmetric solutions of N=2, D=4 gauged supergravity coupled to abelian
vector multiplets were classified, we construct the first examples of genuine
supersymmetric black holes in AdS_4 with nonconstant scalar fields. This is
done for various choices of the prepotential, amongst others for the STU model.
These solutions permit to study the BPS attractor flow in AdS. We also
determine the most general supersymmetric static near-horizon geometry and
obtain the attractor equations in gauged supergravity. As a general feature we
find the presence of flat directions in the black hole potential, i.e.,
generically the values of the moduli on the horizon are not completely
specified by the charges. For one of the considered prepotentials, the
resulting moduli space is determined explicitely. Still, in all cases, we find
that the black hole entropy depends only on the charges, in agreement with the
attractor mechanism.Comment: 25 pages, uses JHEP3.cl
Branes, central charges and U-duality invariant BPS conditions
In extended supergravity theories there are -brane solutions preserving
different numbers of supersymmetries, depending on the charges, the spacetime
dimension and the number of original supersymmetries (8, 16 or 32). We find
U-duality invariant conditions on the quantized charges which specify the
number of supersymmetries preserved with a particular charge configuration.
These conditions relate U-duality invariants to the picture of intersecting
branes. The analysis is carried out for all extended supergravities with 16 or
32 supersymmetries in various dimensions.Comment: 15 pages, no figures, typos correcte
Deux indicateurs probabilistes de retournement cyclique pour l’économie française.
This paper proposes two new coincident probabilistic cyclical indicators developed by the Bank of France in order to follow, on a monthly basis, the French economic activity. The first one is an indicator which aims at detecting the turning points of the acceleration cycle while the second one is dedicated to the follow-up of recession phases in the industrial sector. Both indicators are based on the methodology of Markov-Switching models and use only for input the Bank of France monthly business survey. An historical validation since 1998 points out to the interest and the complementarity of both indicators for the short-term economic diagnosis. This kind of indicators provides with an original and additional conjonctural qualitative information by comparison with more classical quantitative tools aiming at estimating the GDP growth rate.Business cycle ; Acceleration cycle ; Probabilistic indicator ; Markov-Switching models ; Surveys.
On Symmetries of Extremal Black Holes with One and Two Centers
After a brief introduction to the Attractor Mechanism, we review the
appearance of groups of type E7 as generalized electric-magnetic duality
symmetries in locally supersymmetric theories of gravity, with particular
emphasis on the symplectic structure of fluxes in the background of extremal
black hole solutions, with one or two centers. In the latter case, the role of
an "horizontal" symmetry SL(2,R) is elucidated by presenting a set of
two-centered relations governing the structure of two-centered invariant
polynomials.Comment: 1+13 pages, 2 Tables. Based on Lectures given by SF and AM at the
School "Black Objects in Supergravity" (BOSS 2011), INFN - LNF, Rome, Italy,
May 9-13 201
Positive energy unitary irreducible representations of D=6 conformal supersymmetry
We give a constructive classification of the positive energy (lowest weight)
unitary irreducible representations of the D=6 superconformal algebras
osp(8*/2N). Our results confirm all but one of the conjectures of Minwalla (for
N=1,2) on this classification. Our main tool is the explicit construction of
the norms of the states that has to be checked for positivity. We give also the
reduction of the exceptional UIRs.Comment: 27 pages, TeX with harvmac, amssym.def, amssym.tex; v.2: minor
corrections and references added; v.3: minor corrections; v.4: to appear in
J. Phys.
Explicit Orbit Classification of Reducible Jordan Algebras and Freudenthal Triple Systems
We determine explicit orbit representatives of reducible Jordan algebras and
of their corresponding Freudenthal triple systems. This work has direct
application to the classification of extremal black hole solutions of N = 2, 4
locally supersymmetric theories of gravity coupled to an arbitrary number of
Abelian vector multiplets in D = 4, 5 space-time dimensions.Comment: 18 pages. Updated to match published versio
The Enhancon, Black Holes, and the Second Law
We revisit the physics of five-dimensional black holes constructed from D5-
and D1-branes and momentum modes in type IIB string theory compactified on K3.
Since these black holes incorporate D5-branes wrapped on K3, an enhancon locus
appears in the spacetime geometry. With a `small' number of D1-branes, the
entropy of a black hole is maximised by including precisely half as many
D5-branes as there are D1-branes in the black hole. Any attempts to introduce
more D5-branes, and so reduce the entropy, are thwarted by the appearance of
the enhancon locus above the horizon, which then prevents their approach. The
enhancon mechanism thereby acts to uphold the Second Law of Thermodynamics.
This result generalises: For each type of bound state object which can be made
of both types of brane, we show that a new type of enhancon exists at
successively smaller radii in the geometry, again acting to prevent any
reduction of the entropy just when needed. We briefly explore the appearance of
the enhancon in the black hole interior.Comment: 22 pages, 2 figures, latex, epsfig (v2: Fixed trivial typos.
Jordan Pairs, E6 and U-Duality in Five Dimensions
By exploiting the Jordan pair structure of U-duality Lie algebras in D = 3
and the relation to the super-Ehlers symmetry in D = 5, we elucidate the
massless multiplet structure of the spectrum of a broad class of D = 5
supergravity theories. Both simple and semi-simple, Euclidean rank-3 Jordan
algebras are considered. Theories sharing the same bosonic sector but with
different supersymmetrizations are also analyzed.Comment: 1+41 pages, 1 Table; v2 : a Ref. and some comments adde
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