3,274 research outputs found
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
) 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 -generators; we
find that the instanton corrections to the Yukawa couplings are directly
related to the non-vanishing of . 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
. 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
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 authorsâ 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
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
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
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
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