4,993 research outputs found
A Computer Algorithm For Engineering Off-Shell Multiplets With Four Supercharges On The World Sheet
We present an adinkra-based computer algorithm implemented in a Mathematica
code and use it in a limited demonstration of how to engineer off-shell,
arbitrary N-extended world-sheet supermultiplets. Using one of the outputs from
this algorithm, we present evidence for the unexpected discovery of a
previously unknown 8 - 8 representation of N = 2 world sheet supersymmetry. As
well, we uncover a menagerie of (p, q) = (3, 1) world sheet supermultiplets.Comment: 52 pages, 64 figures, LaTeX twice, added note in proof, addition of
comments about gauge invariance for 4D vector & tensor supermultiplet
A Note on Embedding of M-Theory Corrections into Eleven-Dimensional Superspace
By analyzing eleven-dimensional superspace fourth-rank superfield strength
F-Bianchi identities, we show that M-theory corrections to eleven-dimensional
supergravity can not be embedded into the mass dimension zero constraints, such
as the (\g^{a b})_{\a\b} X_{a b}{}^c or i (\g^{a_1... a_5})_{\a\b} X_{a_1...
a_5}{}^c -terms in the supertorsion constraint T_{\a\b}{}^c. The only possible
modification of superspace constraint at dimension zero is found to be the
scaling of F_{\a\b c d} like F_{\a\b c d} = (1/2) \big(\g_{c d}\big)_{\a\b}
e^\Phi for some real scalar superfield \Phi, which alone is further shown not
enough to embed general M-theory corrections. This conclusion is based on the
dimension zero F-Bianchi identity under the two assumptions: (i) There are no
negative dimensional constraints on the F-superfield strength: F_{\a\b\g\d} =
F_{\a\b\g d} =0; (ii) The supertorsion T-Bianchi identities and F-Bianchi
identities are not modified by Chern-Simons terms. Our result can serve as a
powerful tool for future exploration of M-theory corrections embedded into
eleven-dimensional superspace supergravity.Comment: 14 pages, latex, some minor typos corrected, as well as old section 5
deleted, due to the subtlety about Chern-Simons term in F-Bianchi identitie
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
A Superfield for Every Dash-Chromotopology
The recent classification scheme of so-called adinkraic off-shell
supermultiplets of N-extended worldline supersymmetry without central charges
finds a combinatorial explosion. Completing our earlier efforts, we now
complete the constructive proof that all of these trillions or more of
supermultiplets have a superfield representation. While different as
superfields and supermultiplets, these are still super-differentially related
to a much more modest number of minimal supermultiplets, which we construct
herein.Comment: 13 pages, integrated illustration
Effective Symmetries of the Minimal Supermultiplet of N = 8 Extended Worldline Supersymmetry
A minimal representation of the N = 8 extended worldline supersymmetry, known
as the `ultra-multiplet', is closely related to a family of supermultiplets
with the same, E(8) chromotopology. We catalogue their effective symmetries and
find a Spin(4) x Z(2) subgroup common to them all, which explains the
particular basis used in the original construction. We specify a constrained
superfield representation of the supermultiplets in the ultra-multiplet family,
and show that such a superfield representation in fact exists for all adinkraic
supermultiplets. We also exhibit the correspondences between these
supermultiplets, their Adinkras and the E(8) root lattice bases. Finally, we
construct quadratic Lagrangians that provide the standard kinetic terms and
afford a mixing of an even number of such supermultiplets controlled by a
coupling to an external 2-form of fluxes.Comment: 13 Figure
Cosmological Supergravity from a Massive Superparticle and Super Cosmological Black Holes
We describe in superspace a classical theory of two dimensional
dilaton supergravity with a cosmological constant, both with and without
coupling to a massive superparticle. We give general exact non-trivial
superspace solutions for the compensator superfield that describes the
supergravity in both cases. We then use these compensator solutions to
construct models of two-dimensional supersymmetric cosmological black holes.Comment: 20 pages, Late
Winner of the 2016 Lewis Fry Richardson Award, Paul Collier: Clarity and Compassion in the Study of Civil War
The award committee has chosen Paul Collier as the winner of the 2016 Lewis Fry Richardson Award in particular in recognition of his contributions to the study of civil war. His famous paper on "Greed and grievance in civil war" - published with Anke Hoeffler in 2004, but circulating in draft form since the late 1990s - has been cited over 1000 times in the Web of Science as of mid-July 2016, and has over 5000 citations in Google Scholar. The jury also highlighted the key role of Collier's work reviving academic research on civil war in the late 1990s, the broader impact of the World Bank group led by Collier in spurring advances in the field as well as stimulating important data collection efforts, as well as his central role in popularizing insights of academic research to a broader audience
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