6,966 research outputs found
The Real Anatomy of Complex Linear Superfields
Recent work on classicication of off-shell representations of N-extended
worldline supersymmetry without central charges has uncovered an unexpectedly
vast number--trillions of even just (chromo)topology types--of so called
adinkraic supermultiplets. Herein, we show by explicit analysis that a
long-known but rarely used representation, the complex linear supermultiplet,
is not adinkraic, cannot be decomposed locally, but may be reduced by means of
a Wess-Zumino type gauge. This then indicates that the already unexpectedly
vast number of adinkraic off-shell supersymmetry representations is but the
proverbial tip of the iceberg.Comment: 21 pages, 4 figure
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
Towards a Unified Theory of Massless Superfields of All Superspins
We describe the ``universal'' action for massless superfields of all
superspins in N = 1, D = 4 anti-de Sitter superspace as a gauge theory of
unconstrained superfields taking their values in the commutative algebra of
analytic functions over a one-sheeted hyperboloid in . The action is
invariant under N = 2 supersymmetry transformations which form a closed algebra
off the mass-shell.Comment: 12 pages, LaTe
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
Chiral supergravity actions and superforms
The superform construction of supergravity actions, christened the "ectoplasm
method," is based on the use of a closed super d-form in the case of d
space-time dimensions. In known examples, such superforms are obtained by
iteratively solving nontrivial cohomological problems. The latter usually makes
this scheme no less laborious than the normal coordinate method for deriving
component actions for matter-coupled supergravity. In this note we present an
alternative procedure to generate required superforms in four space-time
dimensions, which makes use of self-dual vector multiplets. It provides the
shortest derivation of chiral actions in two different theories: (i) N = 1 old
minimal supergravity; and (ii) N = 2 conformal supergravity. The N = 2
superform construction is developed here for the first time. Although our
consideration is restricted to the case of four dimensions, a generalization to
higher dimensions is plausible.Comment: 14 pages; V2: minor correction
On Graph-Theoretic Identifications of Adinkras, Supersymmetry Representations and Superfields
In this paper we discuss off-shell representations of N-extended
supersymmetry in one dimension, ie, N-extended supersymmetric quantum
mechanics, and following earlier work on the subject codify them in terms of
certain graphs, called Adinkras. This framework provides a method of generating
all Adinkras with the same topology, and so also all the corresponding
irreducible supersymmetric multiplets. We develop some graph theoretic
techniques to understand these diagrams in terms of a relatively small amount
of information, namely, at what heights various vertices of the graph should be
"hung".
We then show how Adinkras that are the graphs of N-dimensional cubes can be
obtained as the Adinkra for superfields satisfying constraints that involve
superderivatives. This dramatically widens the range of supermultiplets that
can be described using the superspace formalism and organizes them. Other
topologies for Adinkras are possible, and we show that it is reasonable that
these are also the result of constraining superfields using superderivatives.
The family of Adinkras with an N-cubical topology, and so also the sequence
of corresponding irreducible supersymmetric multiplets, are arranged in a
cyclical sequence called the main sequence. We produce the N=1 and N=2 main
sequences in detail, and indicate some aspects of the situation for higher N.Comment: LaTeX, 58 pages, 52 illustrations in color; minor typos correcte
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
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