27,448 research outputs found
Tetraquark resonances, flip-flop and cherry in a broken glass model
We develop a formalism to study tetraquarks using the generalized flip-flop
potential, which include the tetraquark potential component. Technically this
is a difficult problem, needing the solution of the Schr\"odinger equation in a
multidimensional space. Since the tetraquark may at any time escape to a pair
of mesons, here we study a simplified two-variable toy model and explore the
analogy with a cherry in a glass, but a broken one where the cherry may escape
from. We also compute the decay width in this two-variable picture, solving the
Schr\"odinger equation for the outgoing spherical wave.Comment: 9 pages, 6 figures, 1 table, contribution to the proceedings of
MINI-WORKSHOP BLED 2010: DRESSING HADRONS, Bled (Slovenia), July 4 - 11, 201
First study of the three-gluon static potential in Lattice QCD
We estimate the potential energy for a system of three static gluons in
Lattice QCD. This is relevant for the different models of three-body glueballs
have been proposed in the literature, either for gluons with a constituent
mass, or for massless ones. A Wilson loop adequate to the static hybrid
three-body system is developed. We study different spacial geometries, to
compare the starfish model with the triangle model, for the three-gluon
potential. We also study two different colour structures, symmetric and
antisymmetric, and compare the respective static potentials. A first simulation
is performed in a periodic Lattice, with and fm.Comment: 8 pages, 10 figure
Colour Fields Computed in SU(3) Lattice QCD for the Static Tetraquark System
The colour fields created by the static tetraquark system are computed in
quenched SU(3) lattice QCD, in a 24^3 x 48 lattice at beta=6.2 corresponding to
a lattice spacing a=0.07261(85) fm. We find that the tetraquark colour fields
are well described by a double-Y, or butterfly, shaped flux tube. The two flux
tube junction points are compatible with Fermat points minimizing the total
flux tube length. We also compare the diquark-diantiquark central flux tube
profile in the tetraquark with the quark-antiquark fundamental flux tube
profile in the meson, and they match, thus showing that the tetraquark flux
tubes are composed of fundamental flux tubes.Comment: 5 pages, 7 figures, 0 tables, one reference added, work done partly
under the PT-LQCD Collaboratio
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
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