7,376 research outputs found
Chiral Supergravitons Interacting with a 0-Brane N-Extended NSR Super-Virasoro Group
We continue the development of the actions, S_{AFF}, by examining the cases
where there are N fermionic degrees of freedom associated with a 0-brane. These
actions correspond to the interaction of the N-extended super Virasoro algebra
with the supergraviton and the associated SO(N) gauge field that accompanies
the supermultiplet. The superfield formalism is used throughout so that
supersymmetry is explicit.Comment: PACS: 04.65.+e, 11.15.-q, 11.25.-w, 12.60.
Think Different: Applying the Old Macintosh Mantra to the Computability of the SUSY Auxiliary Field Problem
Starting with valise supermultiplets obtained from 0-branes plus field
redefinitions, valise adinkra networks, and the "Garden Algebra," we discuss an
architecture for algorithms that (starting from on-shell theories and, through
a well-defined computation procedure), search for off-shell completions. We
show in one dimension how to directly attack the notorious "off-shell auxiliary
field" problem of supersymmetry with algorithms in the adinkra network-world
formulation.Comment: 28 pages, 1 figur
LDR structural experiment definition
A study was performed to develop the definition of a structural flight experiment for a large precision segmented reflector that would utilize the Space Station. The objective of the study was to use the Large Deployable Reflector (LDR) baseline configuration for focusing on experiment definition activity which would identify the Space Station accommodation requirements and interface constraints. Results of the study defined three Space Station based experiments to demonstrate the technologies needed for an LDR type structure. The basic experiment configurations are the same as the JPL baseline except that the primary mirror truss is 10 meters in diameter instead of 20. The primary objectives of the first experiment are to construct the primary mirror support truss and to determine its structural and thermal characteristics. Addition of the optical bench, thermal shield and primary mirror segments and alignment of the optical components occur on the second experiment. The structure will then be moved to the payload pointing system for pointing, optical control and scientific optical measurement for the third experiment
Space structure (dynamics and control) theme development
A study was made to define the long-range technical objectives and goals for the Space Structure (Dynamics and Control) theme area. The approach was to evaluate ongoing and proposed technology activities such that the technology gaps and voids could be identified. After the technology needs were identified, a set of recommended experimental activities was defined including the technical objectives of each and their relationship
Risk of Increased Fragmentation Events Due to Low Altitude Large Constellation Spacecraft
Orbital debris experts and industry leaders are concerned about the added hazard that thousands of additional spacecraft would have on the future orbital debris environment. Large constellations proposals plan to deploy spacecraft at altitudes from 1100 km to 1300 km, where fragmentation debris can take thousands of years or longer to decay naturally, while other proposals include deploying spacecraft at station-keeping altitudes from 300 km to 600 km. Although these lower altitude spacecraft are compliant with the 25-year rule, there is still an increased risk of accidental explosions generating high velocity fragments that could damage international spacecraft assets. The NASA Orbital Debris Program Office (ODPO) has conducted several parametric studies that examine the potential negative environmental impacts of large constellation deployments. This study addresses the lower altitude constellations and the potential risk that they impose on the future environment during mission operations. The projected future environment is generated as the average of 100 LEGEND Monte Carlo (MC) simulation runs while adjusting parameters such as average probability of explosion and operational lifetime per constellation. Results of the effect of accidental explosions of large constellation spacecraft on the environment below 600 km altitude are analyzed
D=2 N=(2,2) Semi Chiral Vector Multiplet
We describe a new 1+1 dimensional N=(2,2) vector multiplet that naturally
couples to semi chiral superfields in the sense that the gauged supercovariant
derivative algebra is only consistent with imposing covariantly semi chiral
superfield constraints. It has the advantages that its prepotentials shift by
semi chiral superfields under gauge transformations. We also see that the
multiplet relates the chiral vector multiplet with the twisted chiral vector
multiplet by reducing to either multiplet under appropriate limits without
being reducible in terms of the chiral and twisted chiral vector multiplet.
This is explained from the superspace geometrical point of view as the result
of possessing a symmetry under the discrete supercoordinate transformation that
is responsible for mirror copies of supermultiplets. We then describe how to
gauge a non linear sigma model with semi chiral superfields using the
prepotentials of the new multiplet.Comment: 15 page
Nanocrystal seeding: A low temperature route to polycrystalline Si films
A novel method is presented for growth of polycrystalline silicon films on amorphous substrates at temperatures of 540–575 °C. Grain nucleation and grain growth are performed in two steps, using Si nanocrystals as nuclei ("seeds"). The nanocrystal seeds are produced by excimer laser photolysis of disilane in a room temperature flow cell. Film (grain) growth occurs epitaxially on the seeds in a separate thermal chemical vapor deposition (CVD) step, with growth rates 10–100 times higher than similar CVD growth rates on crystal Si. Grain size and CVD growth rates are dependent on seed coverage, for seed coverage <0.2 monolayers
Effective action of beta-deformed N=4 SYM theory and AdS/CFT
We compute the one-loop effective action in \N=1 conformal SU(N) gauge theory
which is an exactly marginal deformation of the \N=4 SYM theory. We consider an
abelian background of constant \N = 1 gauge field and single chiral scalar.
While for finite N the effective action depends non-trivially on the
deformation parameter \beta, this dependence disappears in the large N limit if
the parameter \beta is real. This conclusion matches the strong-coupling
prediction coming from the form of a D3-brane probe action in the dual
supergravity background: for the simplest choice of the D3-brane position the
probe action happens to be the same as for a D3-brane in AdS_5 x S^5 placed
parallel to the boundary of AdS_5. This suggests that in the real \beta
deformation case there exists a large N non-renormalization theorem for the
4-derivative term in the action.Comment: 15 pages, no figures. V2: comments, reference added. V3: the version
to appear in PR
On 2D N=(4,4) superspace supergravity
We review some recent results obtained in studying superspace formulations of
2D N=(4,4) matter-coupled supergravity. For a superspace geometry described by
the minimal supergravity multiplet, we first describe how to reduce to
components the chiral integral by using ``ectoplasm'' superform techniques as
in arXiv:0907.5264 and then we review the bi-projective superspace formalism
introduced in arXiv:0911.2546. After that, we elaborate on the curved
bi-projective formalism providing a new result: the solution of the covariant
type-I twisted multiplet constraints in terms of a weight-(-1,-1) bi-projective
superfield.Comment: 18 pages, LaTeX, Contribution to the proceedings of the International
Workshop "Supersymmetries and Quantum Symmetries" (SQS'09), Dubna, July
29-August 3 200
Ectoplasm & Superspace Integration Measure for 2D Supergravity with Four Spinorial Supercurrents
Building on a previous derivation of the local chiral projector for a two
dimensional superspace with eight real supercharges, we provide the complete
density projection formula required for locally supersymmetrical theories in
this context. The derivation of this result is shown to be very efficient using
techniques based on the Ectoplasmic construction of local measures in
superspace.Comment: 18 pages, LaTeX; V2: minor changes, typos corrected, references
added; V3: version to appear in J. Phys. A: Math. Theor., some comments and
references added to address a referee reques
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