N=8 Supergravity 4-point Amplitudes

We present the explicit expressions in N=8 supergravity for the bosonic 4-particle tree and 1-loop amplitudes including vectors and scalars. We also present the candidate 4-point UV divergences in a form of helicity amplitudes, corresponding to 3-loop manifestly N=8 supersymmetric and Lorentz covariant counterterm. This may shed some light on the 3-loop finiteness of N=8 SG and on a conjectured higher loop finiteness. We perform a supersymmetric deformation to complex momentum of the 4-point generating function including higher-loop counterterms and the 1-loop UV finite amplitudes. Using the explicit form of the scalar part of the 3-loop counterterm and of the 1-loop UV finite scalar 4-point amplitudes we find that they both have an unbroken E7 symmetry. We derive from E7 symmetry the low-energy theorem for the 1-loop n-point amplitudes.Comment: 23 p, 4 figure

P-term Potentials from 4-D Supergravity

P-term inflation arises in some models of brane inflation. Within N=2 supersymmetry the scalar potential contains a vector of Fayet-Iliopoulos (FI) terms $\xi_i$. Depending on the direction of this vector it is possible to get D-term and F-term inflation or a mix of these models. In this paper we review the problems of embedding the P-term model in supergravity and show how these can be solved by considering the truncation from an N=2 theory to N=1. We show that with a simple gauging the scalar potential can include F-term or D-term parts but not both. The gauging can be altered so that both F-terms and D-terms containing FI constants can be included. In all cases we display the inflationary trajectory and, if it exists, the supersymmetric minimum.Comment: 21 pages, no figure

Duality, Central Charges and Entropy of Extremal BPS Black Holes

We report on some general results on the physics of extremal BPS black holes in four and five dimensions. The duality-invariant entropy-formula for all $N>2$ extended supergravities is derived. Its relation with the fixed-scalar condition for the black-hole ``potential energy'' wich extremizes the BPS mass is obtained. BPS black holes preserving different fractions of supersymmetry are classified in a U-duality invariant set up. The latter deals with different orbits of the fundamental representations of the exceptional groups $E_{7(7)}$ and $E_{6(6)}$. We comment upon the interpretation of these results in a string and M-theory framework.Comment: 12 pages, LaTeX; Talk given by S. Ferrara at the STRINGS'97 Conference, 16-21 June 1997, Amsterdam, The Netherland

E{7(7)} Symmetry and Finiteness of N=8 Supergravity

We study N=8 supergravity deformed by the presence of the candidate counterterms. We show that even though they are invariant under undeformed E{7(7)}, all of the candidate counterterms violate the deformed E{7(7)} current conservation. The same conclusion follows from the uniqueness of the Lorentz and SU(8) covariant, E{7(7)} invariant unitarity constraint expressing the 56-dimensional E{7(7)} doublet via 28 independent vectors. Therefore E{7(7)} duality predicts the all-loop UV finiteness of perturbative N=8 supergravity.Comment: 18 page

N=8 BPS Black Holes with 1/2 or 1/4 Supersymmetry and Solvable Lie Algebra Decompositions

In the context of N=8 supergravity we construct the general form of BPS 0--branes that preserve either 1/2 or 1/4 of the original supersymmetry. We show how such solutions are related to suitable decompositions of the 70 dimensional solvable Lie algebra that describes the scalar field sector. We compare our new results to those obtained in a previous paper for the case of 1/8 supersymmetry preserving black holes. Each of the three cases is based on a different solvable Lie algebra decomposition and leads to a different structure of the scalar field evolution and of their fixed values at the horizon of the black hole.Comment: first section restructured, typos corrected, 1 LaTeX file, 37 pages, 2 eps-figure

Near-Horizon Supergravity Superspace

We present a construction of the superspace of maximally supersymmetric adS_{p+2} x S^{d-p-2} near-horizon geometry based entirely on the supergravity constraints of which the bosonic space is a solution. Besides the geometric superfields, i.e. the vielbeine and the spinconnection, we also derive the isometries of the superspace together with the compensating tangent space transformations to all orders in anticommuting superspace coordinates.Comment: 6 pages, contribution to the proceedings of the "mid-term TMR meeting on Quantum Aspects Theories, Supersymmetry and Unification", Corfu, September 20-26, 199

N=8 Counterterms and E7(7) Current Conservation

We examine conservation of the E7(7) Noether-Gaillard-Zumino current in the presence of N=8 supergravity counterterms using the momentum space helicity formalism, which significantly simplifies the calculations. The main result is that the 4-point counterterms at any loop order L are forbidden by the E7(7) current conservation identity. We also clarify the relation between linearized and full non-linear superinvariants as candidate counterterms. This enables us to show that all n-point counterterms at L=7, 8 are forbidden since they provide a non-linear completions of the 4-point ones. This supports and exemplifies our general proof in arXiv:1103.4115 of perturbative UV finiteness of N=8 supergravity.Comment: 18 page

First Order Description of Black Holes in Moduli Space

We show that the second order field equations characterizing extremal solutions for spherically symmetric, stationary black holes are in fact implied by a system of first order equations given in terms of a prepotential W. This confirms and generalizes the results in [14]. Moreover we prove that the squared prepotential function shares the same properties of a c-function and that it interpolates between M^2_{ADM} and M^2_{BR}, the parameter of the near-horizon Bertotti-Robinson geometry. When the black holes are solutions of extended supergravities we are able to find an explicit expression for the prepotentials, valid at any radial distance from the horizon, which reproduces all the attractors of the four dimensional N>2 theories. Far from the horizon, however, for N-even our ansatz poses a constraint on one of the U-duality invariants for the non-BPS solutions with Z \neq 0. We discuss a possible extension of our considerations to the non extremal case.Comment: Some points clarified, a comment on the interpretation of the prepotential W in terms of c-function added, typos corrected. Version to appear on JHE

Vacua of M-theory and string theory

We argue that supersymmetric higher-dimension operators in the effective actions of M-theory and IIB string theory do not affect the maximally supersymmetric vacua: $adS_4\times S^7$ and $adS_7\times S^4$ in M-theory and $adS_5\times S^5$ in IIB string theory. All these vacua are described in superspace by a fixed point with all components of supertorsion and supercurvature being supercovariantly constant. This follows from 32 unbroken supersymmetries and allows us to prove that such vacua are exact.Comment: 16 pages, late

N=2 supergravity models with stable de Sitter vacua

In the present talk I shall review the construction of N=2 supergravity models exhibiting stable de Sitter vacua. These solutions represent the first instance of stable backgrounds with positive cosmological constant in the framework of extended supergravities (N >=2). After briefly reviewing the role of de Sitter space--times in inflationary cosmology, I shall describe the main ingredients which were necessary for the construction of gauged N=2 supergravity models admitting stable solutions of this kind.Comment: Prepared for Workshop on the Quantum Structure of Spacetime and the Geometric Nature of Fundamental Interactions, Leuven, Belgium, September 13-19 200