4,859 research outputs found
On Supermultiplet Twisting and Spin-Statistics
Twisting of off-shell supermultiplets in models with 1+1-dimensional
spacetime has been discovered in 1984, and was shown to be a generic feature of
off-shell representations in worldline supersymmetry two decades later. It is
shown herein that in all supersymmetric models with spacetime of four or more
dimensions, this off-shell supermultiplet twisting, if non-trivial, necessarily
maps regular (non-ghost) supermultiplets to ghost supermultiplets. This feature
is shown to be ubiquitous in all fully off-shell supersymmetric models with
(BV/BRST-treated) constraints.Comment: Extended version, including a new section on manifestly off-shell and
supersymmetric BRST treatment of gauge symmetry; added reference
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
Generalized Attractor Points in Gauged Supergravity
The attractor mechanism governs the near-horizon geometry of extremal black
holes in ungauged 4D N=2 supergravity theories and in Calabi-Yau
compactifications of string theory. In this paper, we study a natural
generalization of this mechanism to solutions of arbitrary 4D N=2 gauged
supergravities. We define generalized attractor points as solutions of an
ansatz which reduces the Einstein, gauge field, and scalar equations of motion
to algebraic equations. The simplest generalized attractor geometries are
characterized by non-vanishing constant anholonomy coefficients in an
orthonormal frame. Basic examples include Lifshitz and Schrodinger solutions,
as well as AdS and dS vacua. There is a generalized attractor potential whose
critical points are the attractor points, and its extremization explains the
algebraic nature of the equations governing both supersymmetric and
non-supersymmetric attractors.Comment: 31 pages, LaTeX; v2, references fixed; v3, minor changes, version to
appear in Phys. Rev.
The identification of a distributed parameter model for a flexible structure
A computational method is developed for the estimation of parameters in a distributed model for a flexible structure. The structure we consider (part of the RPL experiment) consists of a cantilevered beam with a thruster and linear accelerometer at the free end. The thruster is fed by a pressurized hose whose horizontal motion effects the transverse vibration of the beam. The Euler-Bernoulli theory is used to model the vibration of the beam and treat the hose-thruster assembly as a lumped or point mass-dashpot-spring system at the tip. Using measurements of linear acceleration at the tip, it is estimated that the parameters (mass, stiffness, damping) and a Voight-Kelvin viscoelastic structural damping parameter for the beam using a least squares fit to the data. Spline based approximations to the hybrid (coupled ordinary and partial differential equations) system are considered; theoretical convergence results and numerical studies with both simulation and actual experimental data obtained from the structure are presented and discussed
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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