Mach-Based Channel Library

[No Abstract

QCD Flux Tubes as Sigma Model Relics

We describe flux tubes and their interactions in a low energy sigma model induced by SU(\NF) \goto SO(\NF) flavor symmetry breaking in $SO(N_c)$ QCD. Gauge confinement manifests itself in the low energy theory through flux tube interactions with unscreened sources. The flux tubes which mediate confinement also illustrate an interesting ambiguity in defining global Alice strings.Comment: 12 pages (REVTEX) plus one figur

Structure of the constituent quark and quark distributions of hadrons

We study the structure of constituent quarks by dressing bare quarks with the Goldstone bosons and its implications for quark distribution functions of hadrons $f_1(x)$, $g_1(x)$ and $h_1(x)$. In particular we discuss effects of the dressing on the nucleon spin structure, and find that contributions to chiral-odd $h_1(x)$ is quite different from those to $g_1 (x)$, which can be measured in the semi-inclusive polarized deep inelastic scattering.Comment: 7 pages, LaTeX, 4 figures are included using epsfig.sty, talk presented at QULEN97, to appear in the proceedings, Complete PS fils is also available at http://WWW.physik.tu-muenchen.de/~ksuzuki/publication.htm

Chiral Perturbation Theory for phi -> rho gamma gamma and phi -> omega gamma gamma

We predict differential decay distributions for phi->rho gamma gamma and phi -> omega gamma gamma using chiral perturbation theory. We also consider the isospin violating decay phi -> omega pi^0. Experimental information on these decays can be used to determine couplings in the heavy vector meson chiral Lagrangian.Comment: It was shown by P. Ko et al., hep-ph/9510205 (Phys. Lett. B366 (1996) 287), that there is a etaprime pole contribution that dominates over what we calculate

Motion detection in astronomical and ice floe images

Two approaches are presented for establishing correspondence between small areas in pairs of successive images for motion detection. The first one, based on local correlation, is used on a pair of successive Voyager images of the Jupiter which differ mainly in locally variable translations. This algorithm is implemented on a sequential machine (VAX 780) as well as the Massively Parallel Processor (MPP). In the case of the sequential algorithm, the pixel correspondence or match is computed on a sparse grid of points using nonoverlapping windows (typically 11 x 11) by local correlations over a predetermined search area. The displacement of the corresponding pixels in the two images is called the disparities to cubic surfaces. The disparities at points where the error between the computed values and the surface values exceeds a particular threshold are replaced by the surface values. A bilinear interpolation is then used to estimate disparities at all other pixels between the grid points. When this algorithm was applied at the red spot in the Jupiter image, the rotating velocity field of the storm was determined. The second method of motion detection is applicable to pairs of images in which corresponding areas can experience considerable translation as well as rotation

Parallel algorithm for determining motion vectors in ice floe images by matching edge features

A parallel algorithm is described to determine motion vectors of ice floes using time sequences of images of the Arctic ocean obtained from the Synthetic Aperture Radar (SAR) instrument flown on-board the SEASAT spacecraft. Researchers describe a parallel algorithm which is implemented on the MPP for locating corresponding objects based on their translationally and rotationally invariant features. The algorithm first approximates the edges in the images by polygons or sets of connected straight-line segments. Each such edge structure is then reduced to a seed point. Associated with each seed point are the descriptions (lengths, orientations and sequence numbers) of the lines constituting the corresponding edge structure. A parallel matching algorithm is used to match packed arrays of such descriptions to identify corresponding seed points in the two images. The matching algorithm is designed such that fragmentation and merging of ice floes are taken into account by accepting partial matches. The technique has been demonstrated to work on synthetic test patterns and real image pairs from SEASAT in times ranging from .5 to 0.7 seconds for 128 x 128 images

A study of point discharge current observations in the thunderstorm environment at a tropical station during the year 1987 and 1988

The results of the measurements of point discharge current observations at Pune, India, during years 1987 and 1988 are presented by categorizing and studying their number of spells, polar current average durations, and current magnitudes in day-time and night-time conditions. While the results showed that the thunderstorm activity occupies far more day-time than the night-time the level of current magnitudes remains nearly the same in the two categories

Dynamical Polarizabilities of SU(3) Octet of Baryons

We present calculations and an analysis of the spin-independent dipole electric and magnetic dynamical polarizabilities for the lowest in mass SU(3) octet of baryons. These extensive calculations are made possible by the recent implementation of semi-automatized calculations in Chiral Perturbation Theory which allows evaluating dynamical spin-independent electromagnetic polarizabilities from Compton scattering up to next-to-the-leading order. Our results are in good agreement with calculations performed for nucleons found in the literature. The dependencies for the range of photon energies up to 1 GeV, covering the majority of the meson photo production channels, are analyzed. The separate contributions into polarizabilities from the various baryon meson clouds are studied.Comment: 10 pages, 7 figures, extended analysis of hyperon polarizabilitie