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

Picard-Fuchs Equations and Special Geometry

We investigate the system of holomorphic differential identities implied by special K\"ahlerian geometry of four-dimensional N=2 supergravity. For superstring compactifications on \cy threefolds these identities are equivalent to the Picard-Fuchs equations of algebraic geometry that are obeyed by the periods of the holomorphic three-form. For one variable they reduce to linear fourth-order equations which are characterized by classical $W$-generators; we find that the instanton corrections to the Yukawa couplings are directly related to the non-vanishing of $w_4$. We also show that the symplectic structure of special geometry can be related to the fact that the Yukawa couplings can be written as triple derivatives of some holomorphic function $F$. Moreover, we give the precise relationship of the Yukawa couplings of special geometry with three-point functions in topological field theory.Comment: 43 page

Supersymmetric completion of M-theory 4D-gauge algebra from twisted tori and fluxes

We present the supersymmetric completion of the M-theory free differential algebra resulting from a compactification to four dimensions on a twisted seven-torus with 4-form and 7-form fluxes turned on. The super--curvatures are given and the local supersymmetry transformations derived. Dual formulations of the theory are discussed in connection with classes of gaugings corresponding to diverse choices of vacua. This also includes seven dimensional compactifications on more general spaces not described by group manifolds.Comment: 19 pages, LaTeX, typos corrected, references adde

Gauged extended supergravity without cosmological constant: no-scale structure and supersymmetry breaking

We consider the interplay of duality symmetries and gauged isometries of supergravity models giving N-extended, spontaneously broken supergravity with a no-scale structure. Some examples, motivated by superstring and M-theory compactifications are described.Comment: AMS-LaTeX, 16 pages. Invited paper to appear in the review section of the IJMP

Kahler Anomalies in Supergravity and Flux Vacua

We review the subject of Kahler anomalies in gauged supergravity, emphasizing that field equations are inconsistent when the Kahler potential is non-invariant under gauge transformations or when there are elementary Fayet-Iliopoulos couplings. Flux vacua solutions of string theory with gauged U(1) shift symmetries appear to avoid this problem. The covariant Kahler anomalies involve tensors which are composite functions of the scalars as well as the gauge field strength and space-time curvature tensors. Anomaly cancellation conditions will be discussed in a sequel to this paper.Comment: 29 pages; v2: revised presentation, section on Fayet-Iliopoulos couplings cut, effects of gauginos on anomalies included, references adde

On massive tensor multiplets

Massive tensor multiplets have recently been scrutinized in hep-th/0410051 and hep-th/0410149, as they appear in orientifold compactifications of type IIB string theory. Here we formulate several dually equivalent models for massive N = 1, N=2 tensor multiplets in four space-time dimensions. In the N = 2 case, we employ harmonic and projective superspace techniques.Comment: 17 pages, LaTeX, no figures; V2: reference adde

Collision Risk Studies with 6DOF Flight Simulations when Aerodrome Obstacle Standards Cannot Be Met

This paper presents an e ective methodology to assess the safety of aircraft operations when aero- drome obstacle standards cannot be met. The re- search addresses the cases of potential airplane impact with on-ground obstacles after an engine failure. The discussion focuses on how statistical studies can be supported by deterministic analy- ses of flight trajectories generated with 6 degree- of-freedom (6DoF) flight simulations. The pro- posed approach is illustrated by introducing a practical example coming from the authors’ pro- fessional experience; in the selected scenario a hypothetical wind farm has to be located in prox- imity of an aerodrome but some of the wind tur- bines intrude the conventional airspace required by ICAO to ensure safe and regular aircraft op- erations. The paper presents the relevant safety requirements applicable around airports and in- troduces a preliminary evaluation technique of the theoretical collision risk (CR) based on the open source flight dynamics model (FDM) soft- ware JSBSim. Finally, a Monte Carlo analysis is presented as an additional step to refine the CR assessment

Measurement of the radiation field surrounding the Collider Detector at Fermilab

We present here the first direct and detailed measurements of the spatial distribution of the ionizing radiation surrounding a hadron collider experiment. Using data from two different exposures we measure the effect of additional shielding on the radiation field around the Collider Detector at Fermilab (CDF). Employing a simple model we parameterize the ionizing radiation field surrounding the detector.Comment: PDF document, 5 pages, including 10 encapsulated postscript figures: Proceedings for the IEEE/NSS-MIC 2003 Conference, Portland, Oregon, October 19-25, 200

N=4 supergravity for Type IIB on T^6/Z_2 in presence of fluxes

We report on the construction of four dimensional gauged supergravity models that can be interpreted as type IIB orientifold compactification in presence of 3-form fluxes and D3--branes. We mainly address our attention to the symplectic embedding of the U-duality group of the theory and the consequent choice of the gauge group, whose four dimensional killing vectors are the remnant of the ten dimensional fluxes. We briefly discuss the structure of the scalar potential arising from the gauging and the properties of the killing vectors in order to preserve some amount of supersymmetry.Comment: LaTeX, iopart class, 9 pages, Contribution to the proceedings of the workshop of the RTN Network "The quantum structure of space-time and the geometric nature of fundamental interactions",Copenhagen, September 2003 2nd version, references adde