43,594 research outputs found
Classification of Triadic Chord Inversions Using Kohonen Self-organizing Maps
In this paper we discuss the application of the Kohonen Selforganizing
Maps to the classification of triadic chords in inversions and root
positions. Our motivation started in the validation of Schönberg´s hypotheses of
the harmonic features of each chord inversion. We employed the Kohonen
network, which has been generally known as an optimum pattern classification
tool in several areas, including music, to verify that hypothesis. The outcomes
of our experiment refuse the Schönberg´s assumption in two aspects: structural
and perceptual/functional
Nematic liquid crystal dynamics under applied electric fields
In this paper we investigate the dynamics of liquid crystal textures in a
two-dimensional nematic under applied electric fields, using numerical
simulations performed using a publicly available LIquid CRystal Algorithm
(LICRA) developed by the authors. We consider both positive and negative
dielectric anisotropies and two different possibilities for the orientation of
the electric field (parallel and perpendicular to the two-dimensional lattice).
We determine the effect of an applied electric field pulse on the evolution of
the characteristic length scale and other properties of the liquid crystal
texture network. In particular, we show that different types of defects are
produced after the electric field is switched on, depending on the orientation
of the electric field and the sign of the dielectric anisotropy.Comment: 7 pages, 12 figure
First study of the gluon-quark-antiquark static potential in SU(3) Lattice QCD
We study the long distance interaction for hybrid hadrons, with a static
gluon, a quark and an antiquark with lattice QCD techniques. A Wilson loop
adequate to the static hybrid three-body system is developed and, using a 24^3
x 48 periodic lattice with beta=6.2 and a ~ 0.075 fm, two different geometries
for the gluon-quark segment and the gluon-antiquark segment are investigated.
When these segments are perpendicular, the static potential is compatible with
confinement realized with a pair of fundamental strings, one linking the gluon
to the quark and another linking the same gluon to the antiquark. When the
segments are parallel and superposed, the total string tension is larger and
agrees with the Casimir Scaling measured by Bali. This can be interpreted with
a type-II superconductor analogy for the confinement in QCD, with repulsion of
the fundamental strings and with the string tension of the first topological
excitation of the string (the adjoint string) larger than the double of the
fundamental string tension.Comment: 4 pages RevTeX, 4 figure
Schwinger-Dyson equations and the quark-antiquark static potential
In lattice QCD, a confining potential for a static quark-antiquark pair can
be computed with the Wilson loop technique. This potential, dominated by a
linear potential at moderate distances, is consistent with the confinement with
a flux tube, an extended and scalar system also directly observable in lattice
QCD. Quantized flux tubes have also been observed in another class of
confinement, the magnetic confinement in type II superconductors. On the other
hand the solution of Schwinger Dyson Equations, say with the Landau gauge
fixing and the truncation of the series of Feynman diagrams, already at the
rainbow level for the self energy and at the ladder level for the Bethe
Salpeter equation, provides a signal of a possible inverse quartic potential in
momentum space derived from one gluon and one ghost exchange, consistent with
confinement. Here we address the successes, difficulties and open problems of
the matching of these two different perspectives of confinement, the
Schwinger-Dyson perspective versus the flux tube perspective.Comment: 12 pages, 18 figures; talk presented at QCD-TNT, Trento, 7-11 sep
200
Gluon and Ghost Dynamics from Lattice QCD
The two point gluon and ghost correlation functions and the three gluon
vertex are investigated, in the Landau gauge, using lattice simulations. For
the two point functions, we discuss the approach to the continuum limit looking
at the dependence on the lattice spacing and volume. The analytical structure
of the propagators is also investigated by computing the corresponding spectral
functions using an implementation of the Tikhonov regularisation to solve the
integral equation. For the three point function we report results when the
momentum of one of the gluon lines is set to zero and discuss its implications.Comment: Proceedings of Light Cone 2016, held in Lisbon, September 2016. Minor
changes in text. To appear in Few B Sy
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