13,713 research outputs found

### Superspace Representations of SU(2,2/N) Superalgebras and Multiplet Shortening

We derive massless and massive representations of all SU(2,2/N) superalgebras
by using superfields defined in "harmonic superspace". This method allows one
to easily construct "short superfields" which are relevant in the analysis of
the AdS/CFT correspondence.Comment: Talk given at the TMR Conference on Quantum Aspects of Gauge
Theories, Supersymmetry and Unification, Paris, 1-7 September 199

### 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

### Dualities Compositeness and Spacetime Structure of 4d Extreme Stringy Black Holes

We study the BPS black hole solutions of the (truncated) action for heterotic
string theory compactified on a six-torus. The O(3,Z) duality symmetry of the
theory, together with the bound state interpretation of extreme black holes, is
used to generate the whole spectrum of the solutions. The corresponding
spacetime structures, written in terms of the string metric, are analyzed in
detail. In particular, we show that only the elementary solutions present naked
singularities. The bound states have either null singularities (electric
solutions) or are regular (magnetic or dyonic solutions) with near-horizon
geometries given by the product of two 2d spaces of constant curvature. The
behavior of some of these solutions as supersymmetric attractors is discussed.
We also show that our approach is very useful to understand some of the
puzzling features of charged black hole solutions in string theory.Comment: 17 pages, LaTex, no figure

### Regular R-R and NS-NS BPS black holes

We show in a precise group theoretical fashion how the generating solution of
regular BPS black holes of N=8 supergravity, which is known to be a solution
also of a simpler N=2 STU model truncation, can be characterized as NS-NS or
R-R charged according to the way the corresponding STU model is embedded in the
original N=8 theory. Of particular interest is the class of embeddings which
yield regular BPS black hole solutions carrying only R-R charge and whose
microscopic description can possibly be given in terms of bound states of
D-branes only. The microscopic interpretation of the bosonic fields in this
class of STU models relies on the solvable Lie algebra (SLA) method. In the
present article we improve this mathematical technique in order to provide two
distinct descriptions for type IIA and type IIB theories and an algebraic
characterization of S*T--dual embeddings within the N=8,d=4 theory. This
analysis will be applied to the particular example of a four parameter
(dilatonic) solution of which both the full macroscopic and microscopic
descriptions will be worked out.Comment: latex, 30 pages. Final version to appear on Int.J.Mod.Phy

### Central Extensions of Supersymmetry in Four and Three Dimensions

We consider the maximal central extension of the supertranslation algebra in
d=4 and 3, which includes tensor central charges associated to topological
defects such as domain walls (membranes) and strings. We show that for all
N-extended superalgebras these charges are related to nontrivial configurations
on the scalar moduli space. For N=2 theories obtained from compactification on
Calabi-Yau threefolds, we give an explicit realization of the moduli-dependent
charges in terms of wrapped branes.Comment: 11 pages. Sections 2 and 4 expanded, misprints corrected, references
adde

### String Quantum Symmetries From Picard-Fuchs Equations And Their Monodromy

Local and global properties of the moduli space of Calabi--Yau type
compactifications determine the low energy parameters of the string effective
action. We show that the moduli space geometry is entirely encoded in the
Picard--Fuchs equations for the periods of the Calabi--Yau
$H^{(3)}$--cohomology.Comment: 33 pages, plain TeX, CERN-TH.6777/93,POLFIS-TH.24/9

### Dyonic Masses from Conformal Field Strengths in D even Dimensions

We show that D/2--form gauge fields in D even dimensions can get a mass with
both electric and magnetic contributions when coupled to conformal
field--strengths whose gauge potentials is are \frac {D-2}{2}- forms. Denoting
by e^I_\L and m^{I\L} the electric and magnetic couplings, gauge invariance
requires: e^I_\L m^{J\L}\mp e^J_\L m^{I\L}=0, where I,\L= 1... m denote the
species of gauge potentials of degree D/2 and gauge fields of degree D/2-1,
respectively. The minus and plus signs refer to the two different cases D=4n
and D=4n+2 respectively and the given constraints are respectively {\rm
{Sp}}(2m) and {\rm {O}}(m,m) invariant. For the simplest examples, (I,\L=1 for
D=4n and I,\L=1,2 for D=4n+2) both the e,m quantum numbers contribute to the
mass \m=\sqrt {e^2 +m^2} . This phenomenon generalizes to $D$ even dimensions
the coupling of massive antisymmetric tensors which appear in D=4 supergravity
Lagrangians which derive from flux compactifications in higher dimensions. For
D=4 we give the supersymmetric generalization of such couplings using N=1
superspace.Comment: 11 pages, LaTeX source, typos corrected. Version to appear on
Phys.Lett.

### Superconformal Field Theories, Multiplet Shortening, and the AdS$_5$/SCFT$_4$ Correspondence

We review the unitarity bounds and the multiplet shortening of UIR's of 4
dimensional superconformal algebras $SU(2,2|N)$, ($N=1,2,4$) in view of their
dual role in the AdS/SCFT correspondence. Some applications to KK spectra,
non-perturbative states and stringy states are given.Comment: minor changes, references adde

### Gauge Fields and Singletons of $AdS_{2p+1}$

We show that $p$-forms on $AdS_{2p+1}$ describe both singletons and massless
particles. On the $2p$-dimensional boundary the singleton $p$-form Lagrangian
reduces to the conformally invariant functional $\int F^2$. All the
representations, singletons as well as massless, are zero center modules and
involve a vacuum mode. Two- and three-form singleton fields are required by
supersymmetry in AdS$_5$ and AdS$_7$ supergravity respectively.Comment: tex file, 13 page

### Some Pathways in non-Linear Supersymmetry: Special Geometry Born-Infeld's, Cosmology and dualities

This review is devoted to some aspects of non-linear Supersymmetry in four
dimensions that can be efficiently described via nilpotent superfields, in both
rigid and curved Superspace. Our focus is mainly on the partial breaking of
rigid $N=2$ Supersymmetry and on a class of generalized Born-Infeld systems
that originate from Special Geometry and on some prototype cosmological models,
starting from the Supergravity embedding of Starobinsky inflation. However, as
an aside we also review briefly some interesting two-field extensions of the
Born-Infeld Lagrangian whose field equations enjoy extended duality symmetries.Comment: Contribution to the Proceedings of "Group Theory, Probability, and
the Structure of Spacetime", A Conference on the Occasion of Professor V.S.
Varadarajan's Retirement, UCLA Mathematics Department, November 7-9, 2014. To
appear in a special issue of "p-Adic Numbers, Ultrametric Analysis and
Applications". 35 pages LaTeX, 1 eps figure. Typos corrected, reference adde

- âŠ