6,931 research outputs found
Quantum mechanics over a q-deformed (0+1)-dimensional superspace
We built up a explicit realization of (0+1)-dimensional q-deformed superspace
coordinates as operators on standard superspace. A q-generalization of
supersymmetric transformations is obtained, enabling us to introduce scalar
superfields and a q-supersymmetric action. We consider a functional integral
based on this action. Integration is implemented, at the level of the
coordinates and at the level of the fields, as traces over the corresponding
representation spaces. Evaluation of these traces lead us to standard
functional integrals. The generation of a mass term for the fermion field
leads, at this level, to an explicitely broken version of supersymmetric
quantum mechanics.Comment: 11 pages, Late
7-Li(p,n) Nuclear Data Library for Incident Proton Energies to 150 MeV
We describe evaluation methods that make use of experimental data, and
nuclear model calculations, to develop an ENDF-formatted data library for the
reaction p + Li7 for incident protons with energies up to 150 MeV. The
important 7-Li(p,n_0) and 7-Li(p,n_1) reactions are evaluated from the
experimental data, with their angular distributions represented using Lengendre
polynomial expansions. The decay of the remaining reaction flux is estimated
from GNASH nuclear model calculations. The evaluated ENDF-data are described in
detail, and illustrated in numerous figures. We also illustrate the use of
these data in a representative application by a radiation transport simulation
with the code MCNPX.Comment: 11 pages, 8 figures, LaTeX, submitted to Proc. 2000 ANS/ENS
International Meeting, Nuclear Applications of Accelerator Technology
(AccApp00), November 12-16, Washington, DC, US
NMR evidence for Friedel-like oscillations in the CuO chains of ortho-II YBaCuO
Nuclear magnetic resonance (NMR) measurements of CuO chains of detwinned
Ortho-II YBaCuO (YBCO6.5) single crystals reveal unusual and
remarkable properties. The chain Cu resonance broadens significantly, but
gradually, on cooling from room temperature. The lineshape and its temperature
dependence are substantially different from that of a conventional spin/charge
density wave (S/CDW) phase transition. Instead, the line broadening is
attributed to small amplitude static spin and charge density oscillations with
spatially varying amplitudes connected with the ends of the finite length
chains. The influence of this CuO chain phenomenon is also clearly manifested
in the plane Cu NMR.Comment: 4 pages, 3 figures, refereed articl
Social Tagging: Exploring the Image, the Tags, and the Game
An increasing amount of images are being uploaded, shared, and retrieved on the Web. These large image collections need to be properly stored, organized and easily retrieved. Tags have a key role in image retrieval but it is difficult for those who upload the images to also undertake the quality tag assignment for potential future retrieval by others. Relying on professional keyword assignment is not a practical option for large image collections due to resource constraints. Although a number of content-based image retrieval systems have been launched, they have not demonstrated sufficient utility on large-scale image sources on the web, and are usually used as a supplement to existing text-based image retrieval systems. An alternative to professional image indexing can be social tagging -- with two major types being photo-sharing networks and image labeling games. Here we analyze these applications to evaluate their usefulness from the semantic point of view. We also investigate whether social tagging behaviour can be managed. The findings of the study have shown that social tagging can generate a sizeable number of tags that can be classified as interpretive for an image, and that tagging behaviour has a manageable and adjustable nature depending on tagging guidelines
On a nonstandard two-parametric quantum algebra and its connections with and
A quantum algebra associated with a nonstandard
-matrix with two deformation parameters is studied and, in
particular, its universal -matrix is derived using Reshetikhin's
method. Explicit construction of the -dependent nonstandard -matrix
is obtained through a coloured generalized boson realization of the universal
-matrix of the standard corresponding to a
nongeneric case. General finite dimensional coloured representation of the
universal -matrix of is also derived. This
representation, in nongeneric cases, becomes a source for various
-dependent nonstandard -matrices. Superization of leads to the super-Hopf algebra . A contraction
procedure then yields a -deformed super-Heisenberg algebra
and its universal -matrix.Comment: 17pages, LaTeX, Preprint No. imsc-94/43 Revised version: A note added
at the end of the paper correcting and clarifying the bibliograph
Solving the Frustrated Spherical Model with q-Polynomials
We analyse the Spherical Model with frustration induced by an external gauge
field. In infinite dimensions, this has been recently mapped onto a problem of
q-deformed oscillators, whose real parameter q measures the frustration. We
find the analytic solution of this model by suitably representing the
q-oscillator algebra with q-Hermite polynomials. We also present a related
Matrix Model which possesses the same diagrammatic expansion in the planar
approximation. Its interaction potential is oscillating at infinity with period
log(q), and may lead to interesting metastability phenomena beyond the planar
approximation. The Spherical Model is similarly q-periodic, but does not
exhibit such phenomena: actually its low-temperature phase is not glassy and
depends smoothly on q.Comment: Latex, 14 pages, 2 eps figure
- …