271 research outputs found

### R-Symmetry, twisted N=2 Theory and the Role of the Dilaton

We discuss R-symmetry in locally supersymmetric $N=2$ gauge theories coupled
to hypermultiplets, which can be viewed as effective theories of heterotic
string models. In this type of supergravities a suitable R-symmetry exists and
can be used to topologically twist the theory. The vector multiplet of the
dilaton-axion field has a different R-charge assignment with respect to the
other vector multiplets.Comment: Proceedings of ``Susy95'', Palaiseaux, Ecole Polytechnique, May 95
LaTex, 8 pg

### N=1 and N=2 pure supergravities on a manifold with boundary

Working in the geometric approach, we construct the lagrangians of N=1 and
N=2 pure supergravity in four dimensions with negative cosmological constant,
in the presence of a non trivial boundary of space-time. We find that the
supersymmetry invariance of the action requires the addition of topological
terms which generalize at the supersymmetric level the Gauss-Bonnet term.
Supersymmetry invariance is achieved without requiring Dirichlet boundary
conditions on the fields at the boundary, rather we find that the boundary
values of the fieldstrengths are dynamically fixed to constant values in terms
of the cosmological constant \Lambda. From a group-theoretical point of view
this means in particular the vanishing of the OSp(N|4)-supercurvatures at the
boundary.Comment: Some clarifications on the N=1 case, typos correcte

### BPS Black Holes in Superegravity

In these lectures we explain the concept of supergravity p-branes and BPS
black holes. Introducing an audience of general relativists to all the
necessary geometry related with extended supergravity (special geometry,
symplectic embeddings and the like) we describe the general properties of N=2
black holes, the structure of central charges in extended supergravity and the
description of black hole entropy as an invariant of the U duality group. Then,
after explaining the concept and the use of solvable Lie algebras we present
the detailed construction of 1/2, 1/4 and 1/8 supersymmetry preserving black
holes in the context of N=8 supergravity. The Lectures are meant to be
introductory and self contained for non supersymmetry experts but at the same
time fully detailed and complete on the subject.Comment: LaTeX, 132 pages, Book.sty. Lecture Notes for the SIGRAV Graduate
School in Contemporary Relativity, Villa Olmo, Como First Course, April 199

### N=(4,2) Chiral Supergravity in Six Dimensions and Solvable Lie Algebras

Decomposition of the solvable Lie algebras of maximal supergravities in D=4,
5 and 6 indicates, at least at the geometrical level, the existence of an
N=(4,2) chiral supergravity theory in D=6 dimensions. This theory, with 24
supercharges, reduces to the known N=6 supergravity after a toroidal
compactification to D=5 and D=4. Evidence for this theory was given long ago by
B. Julia. We show that this theory suffers from a gravitational anomaly equal
to 4/7 of the pure N=(4,0) supergravity anomaly. However, unlike the latter,
the absence of N=(4,2) matter to cancel the anomaly presumably makes this
theory inconsistent. We discuss the obstruction in defining this theory in D=6,
starting from an N=6 five-dimensional string model in the decompactification
limit. The set of massless states necessary for the anomaly cancellation
appears in this limit; as a result the N=(4,2) supergravity in D=6 is extended
to N=(4,4) maximal supergravity theory.Comment: 15 pages, latex, no figure

### On the dualization of Born-Infeld theories

We construct a general Lagrangian, quadratic in the field strengths of $n$
abelian gauge fields, which interpolates between BI actions of n abelian
vectors and actions, quadratic in the vector field-strengths, describing
Maxwell fields coupled to non-dynamical scalars, in which the electric-magnetic
duality symmetry is manifest. Depending on the choice of the parameters in the
Lagrangian, the resulting BI actions may be inequivalent, exhibiting different
duality groups. In particular we find, in our general setting, for different
choices of the parameters, a ${\rm U}(n)$-invariant BI action, possibly related
to the one in \cite{Aschieri:2008ns}, as well as the recently found
$\mathcal{N}=2$ supersymmetric BI action \cite{Ferrara:2014oka}.Comment: 12 pages, LaTeX source, typos corrected, definition of the matrix S
in eq. (3.22) correcte

### D=4, N=2 Supergravity in the Presence of Vector-Tensor Multiplets and the Role of higher p-forms in the Framework of Free Differential Algebras

We thoroughly analyze at the bosonic level, in the framework of Free
Differential Algebras (FDA), the role of 2-form potentials setting in
particular evidence the precise geometric formulation of the anti-Higgs
mechanism giving mass to the tensors. We then construct the (super)-FDA
encoding the coupling of vector-tensor multiplets in D=4, N=2 supergravity, by
solving the Bianchi identities in superspace and thus retrieving the full
theory up to 3-fermions terms in the supersymmetry transformation laws, leaving
the explicit construction of the Lagrangian to future work. We further explore
the extension of the bosonic FDA in the presence of higher p-form potentials,
focussing our attention to the particular case p=3, which would occur in the
construction of D=5, N=2 supergravity where some of the scalars are properly
dualized.Comment: 39 pages, improved introduction, section 4 and Appendices modified,
typos corrected, citations adde

### Observations on the Partial Breaking of $N=2$ Rigid Supersymmetry

We study the partial breaking of $N=2$ rigid supersymmetry for a generic
rigid special geometry of $n$ abelian vector multiplets in the presence of
Fayet-Iliopoulos terms induced by the Hyper-K\"ahler momentum map. By
exhibiting the symplectic structure of the problem we give invariant conditions
for the breaking to occur, which rely on a quartic invariant of the
Fayet-Iliopoulos charges as well as on a modification of the $N=2$ rigid
symmetry algebra by a vector central charge.Comment: 7 pages, LaTeX sourc

### C-map for Born-Infeld theories

The c-map of four dimensional non-linear theories of electromagnetism is
considered both in the rigid case and in its coupling to gravity. In this way
theories with antisymmetric tensors and scalars are obtained, and the three
non-linear representations of N=2 supersymmetry partially broken to N=1
related. The manifest $\mathrm{Sp}(2n)$ and $\mathrm{U}(n)$ covariance of these
theories in their multifield extensions is also exhibited.Comment: Version to appear on Physics Letters

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