9,061 research outputs found
Minimal Higgs Branch for the Breaking of Half of the Supersymmetries in N=2 Supergravity
It is shown that the minimal Higgs sector of a generic N=2 supergravity
theory with unbroken N=1 supersymmetry must contain a Higgs hypermultiplet and
a vector multiplet. When the multiplets parametrize the quaternionic manifold
SO(4,1)/SO(4), and the special Kahler manifold SU(1,1)/U(1), respectively, a
vanishing vacuum energy with a sliding massive spin 3/2 multiplet is obtained.
Potential applications to N=2 low energy effective actions of superstrings are
briefly discussed.Comment: 7 pages, plain Late
Generalized dimensional reduction of supergravity with eight supercharges
We describe some recent investigation about the structure of generic D=4,5
theories obtained by generalized dimensional reduction of D=5,6 theories with
eight supercharges. We relate the Scherk-Schwarz reduction to a special class
of N=2 no-scale gauged supergravities.Comment: Contribution to the proceedings of ``NathFest'' at PASCOS conference,
Northeastern University, Boston, Ma, August 200
Orbits of Exceptional Groups, Duality and BPS States in String Theory
We give an invariant classification of orbits of the fundamental
representations of exceptional groups and which classify
BPS states in string and M theories toroidally compactified to d=4 and d=5. The
exceptional Jordan algebra and the exceptional Freudenthal triple system and
their cubic and quartic invariants play a major role in this classification.
The cubic and quartic invariants correspond to the black hole entropy in d=5
and d=4, respectively. The classification of BPS states preserving different
numbers of supersymmetries is in close parallel to the classification of the
little groups and the orbits of timelike, lightlike and space-like vectors in
Minkowski space. The orbits of BPS black holes in N=2 Maxwell-Einstein
supergravity theories in d=4 and d=5 with symmetric space geometries are also
classified including the exceptional N=2 theory that has and
as its symmety in the respective dimensions.Comment: New references and two tables added, a new section on the orbits of
N=2 Maxwell-Einstein supergravity theories in d=4 and d=5 included and some
minor changes were made in other sections. 17 pages. Latex fil
Non-BPS Attractors in 5d and 6d Extended Supergravity
We connect the attractor equations of a certain class of N=2, d=5
supergravities with their (1,0), d=6 counterparts, by relating the moduli space
of non-BPS d=5 black hole/black string attractors to the moduli space of
extremal dyonic black string d=6 non-BPS attractors. For d = 5 real special
symmetric spaces and for N = 4,6,8 theories, we explicitly compute the flat
directions of the black object potential corresponding to vanishing eigenvalues
of its Hessian matrix. In the case N = 4, we study the relation to the (2,0),
d=6 theory. We finally describe the embedding of the N=2, d=5 magic models in
N=8, d=5 supergravity as well as the interconnection among the corresponding
charge orbits.Comment: 1+27 page
Two-Centered Magical Charge Orbits
We determine the two-centered generic charge orbits of magical N = 2 and
maximal N = 8 supergravity theories in four dimensions. These orbits are
classified by seven U-duality invariant polynomials, which group together into
four invariants under the horizontal symmetry group SL(2,R). These latter are
expected to disentangle different physical properties of the two-centered
black-hole system. The invariant with the lowest degree in charges is the
symplectic product (Q1,Q2), known to control the mutual non-locality of the two
centers.Comment: 1+17 pages, 1 Table; v2: Eq. (3.23) corrected; v3: various
refinements in text and formulae, caption of Table 1 expanded, Footnote and
Refs. added. To appear on JHE
Flat Symplectic Bundles of N-Extended Supergravities, Central Charges and Black-Hole Entropy
In these lectures we give a geometrical formulation of N-extended
supergravities which generalizes N=2 special geometry of N=2 theories. In all
these theories duality symmetries are related to the notion of "flat symplectic
bundles" and central charges may be defined as "sections" over these bundles.
Attractor points giving rise to "fixed scalars" of the horizon geometry and
Bekenstein-Hawking entropy formula for extremal black-holes are discussed in
some details.Comment: Based on lectures given by S. Ferrara at the 5th Winter School on
Mathematical Physics held at the Asia Pacific Center for Theoretical Physics,
Seul (Korea), February 199
On the Super Higgs Effect in Extended Supergravity
We consider the reduction of supersymmetry in N-extended four dimensional
supergravity via the super Higgs mechanism in theories without cosmological
constant. We provide an analysis largely based on the properties of long and
short multiplets of Poincare' supersymmetry. Examples of the super Higgs
phenomenon are realized in spontaneously broken N=8 supergravity through the
Scherk-Schwarz mechanism and in superstring compactification in presence of
brane fluxes. In many models the massive vectors count the difference in number
of the translation isometries of the scalar sigma-model geometries in the
broken and unbroken phase.Comment: Version to appear on Nuclear Physics
Freudenthal Dual Lagrangians
The global U-dualities of extended supergravity have played a central role in
differentiating the distinct classes of extremal black hole solutions. When the
U-duality group satisfies certain algebraic conditions, as is the case for a
broad class of supergravities, the extremal black holes enjoy a further
symmetry known as Freudenthal duality (F-duality), which although distinct from
U-duality preserves the Bekenstein-Hawking entropy. Here it is shown that, by
adopting the doubled Lagrangian formalism, F-duality, defined on the doubled
field strengths, is not only a symmetry of the black hole solutions, but also
of the equations of motion themselves. A further role for F-duality is
introduced in the context of world-sheet actions. The Nambu-Goto world-sheet
action in any (t, s) signature spacetime can be written in terms of the F-dual.
The corresponding field equations and Bianchi identities are then related by
F-duality allowing for an F-dual formulation of Gaillard-Zumino duality on the
world-sheet. An equivalent polynomial "Polyakov- type" action is introduced
using the so-called black hole potential. Such a construction allows for
actions invariant under all groups of type E7, including E7 itself, although in
this case the stringy interpretation is less clear.Comment: 1+16 pages, 1 Table, updated to match published versio
On Invariant Structures of Black Hole Charges
We study "minimal degree" complete bases of duality- and "horizontal"-
invariant homogeneous polynomials in the flux representation of two-centered
black hole solutions in two classes of D=4 Einstein supergravity models with
symmetric vector multiplets' scalar manifolds. Both classes exhibit an SL(2,R)
"horizontal" symmetry. The first class encompasses N=2 and N=4 matter-coupled
theories, with semi-simple U-duality given by SL(2,R) x SO(m,n); the analysis
is carried out in the so-called Calabi-Vesentini symplectic frame (exhibiting
maximal manifest covariance) and until order six in the fluxes included. The
second class, exhibiting a non-trivial "horizontal" stabilizer SO(2), includes
N=2 minimally coupled and N=3 matter coupled theories, with U-duality given by
the pseudo-unitary group U(r,s) (related to complex flux representations).
Finally, we comment on the formulation of special Kaehler geometry in terms of
"generalized" groups of type E7.Comment: 1+24 pages; 1 Table. v2 : Eqs. (1.2) and (1.3) added; Eq. (2.87)
change
R--R Scalars, U--Duality and Solvable Lie Algebras
We consider the group theoretical properties of R--R scalars of string
theories in the low-energy supergravity limit and relate them to the solvable
Lie subalgebra \IG_s\subset U of the U--duality algebra that generates the
scalar manifold of the theory: \exp[\IG_s]= U/H. Peccei-Quinn symmetries are
naturally related with the maximal abelian ideal {\cal A} \subset \IG_s of
the solvable Lie algebra. The solvable algebras of maximal rank occurring in
maximal supergravities in diverse dimensions are described in some detail. A
particular example of a solvable Lie algebra is a rank one,
--dimensional algebra displayed by the classical quaternionic
spaces that are obtained via c-map from the special K\"ahlerian moduli spaces
of Calabi-Yau threefolds.Comment: 17 pages, misprints in Table 2 correcte
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