In supergravity models, the quantum correction to the vacuum energy can be of order M I , if the cutoff is of order the Planck mass M 2 P and Str M2 6= 0. Therefore, the tree level cosmological constant must be nonzero (probably negative). Since the current practice of calculating soft parameters in supergravity models assumes the vanishing tree level cosmological constant, the supergravity cal...

We discuss fine-tuning constraints on supergravity models. The tightest constraints come from the experimental mass limits on two key particles: the lightest CP even Higgs boson and the gluino. We also include the lightest chargino which is relevant when universal gaugino masses are assumed. For each of these particles we show how fine-tuning increases with the experimental mass limit, for four...

A complete one loop analysis of the chromoelectric dipole contribution to the electric dipole moment (edm) of the quarks and of the neutron in N=1 supergravity including the gluino, chargino and neutralino exchange contributions and exhibiting the dependence on the two CP violating phases allowed in the soft SUSY breaking sector of minimal supergravity models is given. It is found that in signi...

We explore some aspects of 4D supergravity theories and F-theory vacua that are parallel to structures in the space of 6D theories. The spectrum and topological terms in 4D supergravity theories correspond to topological data of F-theory geometry, just as in six dimensions. In particular, topological axion-curvature squared couplings appear in 4D theories; these couplings are characterized by v...

It is shown that N=4 gauged supergravity in four dimensions is obtained by compactifying N=1 supergravity in ten dimensions on the group manifold S × S. This could be further related to supergravity in eleven dimensions. Analysis of supersymmetry conditions of N=4 gauged supergravity in four dimensions reveals solutions which preserve 1/4 of the supersymmetries and are characterized by a BPS-mo...

We present a theory of N = 2 chiral supergravity in (10 + 2)-dimensions. This formulation is similar to N = 1 supergravity presented recently using null-vectors in 12D. In order to see the consistency of this theory, we perform a simple dimensional reduction to ten-dimensions, reproducing the type IIB chiral supergravity. We also show that our su-pergravity can be consistent background for supe...

We construct partially localized supergravity counterpart solutions to the 1/2 supersymmetric nonthreshold and the 1/4 supersymmetric threshold bound state BI dyons in the D3-brane Dirac-Born-Infeld theory. Such supergravity solutions have all the parameters of the BI dyons. By applying the type-IIA–type-IIB T-duality transformations to these supergravity solutions, we obtain the supergravity c...

We propose the 4D, N = 1 supergravitational analogues (avatars) of the 4D, N = 1 supersymmetric Born-Infeld action in four dimensions for the first time, by using superspace. In particular, a new Born-Infeld type generalization of the Weyl supergravity action is given. A natural new Born-Infeld type generalization of the Einstein supergravity is found as well. We also brielfy discuss a construc...

We review some results on the connection among supergravity central charges, BPS states and Bekenstein{Hawking entropy. In particular, N = 2 supergravity in four dimensions is studied in detail. For higher N supergravities we just give an account of the general theory specializing the discussion to the N = 8 case when one half of supersymmetry is preserved. We stress the fact that for extremal ...