Five-Brane Effective Field Theory on Calabi-Yau Threefolds

We consider the compactification of the dual form of $N=1$ $D=10$ supergravity on a six-dimensional Calabi-Yau manifold. An $N=1$ off-shell supergravity effective Lagrangian in four dimensions can be constructed in a dual version of the gravitational sector (new-minimal supergravity form). Superspace duality has a simple interpretation in terms of Poincar\'{e} duality of two-form cohomology. The resulting $4D$ Lagrangian may describe the low-energy point-field limit of a five-brane theory, dual to string theory, provided Calabi-Yau spaces are consistent vacua of such dual theory.Comment: 16 pages, LaTeX, CERN-Th.6914/93 POLFIS-TH.04/93 UCLA/93/TEP/1

Orientifolds, Brane Coordinates and Special Geometry

We report on the gauged supergravity analysis of Type IIB vacua on K3x T2/Z2 orientifold in the presence of D3-D7-branes and fluxes. We discuss supersymmetric critical points correspond to Minkowski vacua and the related fixing of moduli, finding agreement with previous analysis. An important role is played by the choice of the symplectic holomorphic sections of special geometry which enter the computation of the scalar potential. The related period matrix N is explicitly given. The relation between the special geometry and the Born--Infeld action for the brane moduli is elucidated.Comment: 24 pages, contribution to the proceedings of "DeserFest", Ann Arbor, Michigan, 3-6 April 200

Spontaneously broken supergravity: Old and new facts

We report on some recent investigations of the structure of the four dimensional gauged supergravity Lagrangian which emerges from flux and Scherk-Schwarz compactifications in higher dimensions. Special attention is given to the gauge structure of M-theory compactified on a seven torus with 4-form and geometrical (spin connection) fluxes turned on. A class of vacua, with flat space-time and described by ``no-scale'' supergravity models, is analyzed.Comment: 14 pages, LaTeX file, imprecise statement correcte

On the Embedding of Space-Time Symmetries into Simple Superalgebras

We explore the embedding of Spin groups of arbitrary dimension and signature into simple superalgebras in the case of extended supersymmetry. The R-symmetry, which generically is not compact, can be chosen compact for all the cases that are congruent mod 8 to the physical conformal algebra so($D-2$,2), $D\geq 3$. An $\rm{so}(1,1)$ grading of the superalgebra is found in all cases. Central extensions of super translation algebras are studied in this framework.Comment: AMS LaTeX, 16 page

Curvatures and potential of M-theory in D=4 with fluxes and twist

We give the curvatures of the free differential algebra (FDA) of M--theory compactified to D=4 on a twisted seven--torus with the 4--form flux switched on. Two formulations are given, depending on whether the 1--form field strengths of the scalar fields (originating from the 3--form gauge field $\hat{A}^{(3)}$) are included or not in the FDA. We also give the bosonic equations of motion and discuss at length the scalar potential which emerges in this type of compactifications. For flat groups we show the equivalence of this potential with a dual formulation of the theory which has the full \rE_{7(7)} symmetry.Comment: 14 pages, LaTeX source, typos correcte

Scalar potential for the gauged Heisenberg algebra and a non-polynomial antisymmetric tensor theory

We study some issues related to the effective theory of Calabi-Yau compactifications with fluxes in Type II theories. At first the scalar potential for a generic electric abelian gauging of the Heisenberg algebra, underlying all possible gaugings of RR isometries, is presented and shown to exhibit, in some circumstances, a "dual'' no-scale structure under the interchange of hypermultiplets and vector multiplets. Subsequently a new setting of such theories, when all RR scalars are dualized into antisymmetric tensors, is discussed. This formulation falls in the class of non-polynomial tensor theories considered long ago by Freedman and Townsend and it may be relevant for the introduction of both electric and magnetic charges.Comment: 11 pages LaTe

N=1 reductions of N=2 supergravity in the presence of tensor multiplets

We consider consistent truncations of N=2 supergravites in the presence of tensor multiplets (dual to hypermultiplets) as they occur in type IIB compactifications on Calabi--Yau orientifolds. We analyze in detail the scalar potentials encompassing these reductions when fluxes are turned on and study vacua of the N=1 phases.Comment: 40 pages, LaTeX, typos corrected, references adde

c--Map,very Special Quaternionic Geometry and Dual Ka\"hler Spaces

We show that for all very special quaternionic manifolds a different N=1 reduction exists, defining a Kaehler Geometry which is ``dual'' to the original very special Kaehler geometry with metric G_{a\bar{b}}= - \partial_a \partial_b \ln V (V={1/6}d_{abc}\lambda^a \lambda^b \lambda^c). The dual metric g^{ab}=V^{-2} (G^{-1})^{ab} is Kaehler and it also defines a flat potential as the original metric. Such geometries and some of their extensions find applications in Type IIB compactifications on Calabi--Yau orientifolds.Comment: 9 pages, LaTeX, typos corrected, comments adde

Twisted tori and fluxes: a no go theorem for Lie groups of weak G_2 holonomy

In this paper we prove the theorem that there exists no 7--dimensional Lie group manifold G of weak G2 holonomy. We actually prove a stronger statement, namely that there exists no 7--dimensional Lie group with negative definite Ricci tensor Ric_{IJ}. This result rules out (supersymmetric and non--supersymmetric) Freund--Rubin solutions of M--theory of the form AdS_4\times G and compactifications with non--trivial 4--form fluxes of Englert type on an internal group manifold G. A particular class of such backgrounds which, by our arguments are excluded as bulk supergravity compactifications corresponds to the so called compactifications on twisted--tori, for which G has structure constants $\tau^K{}_{IJ}$ with vanishing trace $\tau^J{}_{IJ}=0$. On the other hand our result does not have bearing on warped compactifications of M--theory to four dimensions and/or to compactifications in the presence of localized sources (D--branes, orientifold planes and so forth). Henceforth our result singles out the latter compactifications as the preferred hunting grounds that need to be more systematically explored in relation with all compactification features involving twisted tori.Comment: 38 pages, tar file containing LaTeX source and youngtab.st

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