12,684 research outputs found
Building Blocks of Physical States in a Non-Critical 3-Brane on R*S^3
The physical states in a world-volume model of a non-critical 3-brane are
systematically constructed using techniques of four-dimensional conformal field
theories on R*S^3 developed recently. Invariant combinations of creation modes
under a special conformal transformation provide building blocks of physical
states. Any state can be created by acting with such building blocks on a
conformally invariant vacuum in an invariant way under the other conformal
charges: the Hamiltonian and rotation generators on S^3. We explicitly
construct building blocks for scalar, vector and gravitational fields, and
classify them as finite types.Comment: 56 page
The analysis of animate object motion using neural networks and snakes
This paper presents a mechanism for analysing the deformable shape of an object as it moves across the visual field. An object’s outline is detected using active contour models, and is then re-represented as shape, location and rotation invariant axis crossover vectors. These vectors are used as input for a feedforward backpropagation neural network, which provides a confidence value determining how ‘human’ the network considers the given shape to be. The network was trained using simulated human shapes as well as simulated non-human shapes, including dogs, horses and inanimate objects. The network was then tested on unseen objects of these classes, as well as on an unseen object class. Analysis of the network’s confidence values for a given animated object identifies small, individual variations between different objects of the same class, and large variations between object classes. Confidence values for a given object are periodic and parallel the paces being taken by the object
Antilinear spectral symmetry and the vortex zero-modes in topological insulators and graphene
We construct the general extension of the four-dimensional Jackiw-Rossi-Dirac
Hamiltonian that preserves the antilinear reflection symmetry between the
positive and negative energy eigenstates. Among other systems, the resulting
Hamiltonian describes the s-wave superconducting vortex at the surface of the
topological insulator, at a finite chemical potential, and in the presence of
both Zeeman and orbital couplings to the external magnetic field. Here we find
that the bound zero-mode exists only when the Zeeman term is below a critical
value. Other physical realizations pertaining to graphene are considered, and
some novel zero-energy wave functions are analytically computed.Comment: 6 revtex pages; typos corrected, published versio
Twist-3 Effects in Polarized Photon Structure
The polarized photon structure is described by two spin structure functions
and which can be studied in the future polarized ep
or ee colliders. Here we investigate the QCD twist-3 effects in
to the leading order in QCD.Comment: 4 pages, LaTeX2e, 2 eps figures, ws-ijmpa.cls file included, Talk
given at the 3rd Circum-Pan-Pacific Symposium on High Energy Spin Physics,
Beijing, October 8-13, 2001, to appear in the Proceeding
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