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 $24^3 \times 48$ periodic Lattice, with $\beta=6.2$ and $a \sim 0.072$ fm.Comment: 8 pages, 10 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

Spin inversion devices with Fano anti-resonances

Analyzing spin transport of quasi-2D electrons gas moving through a semiconductor wave guide subject to a sectionally homogeneous tilted magnetic field, we found well-defined selection rules for resonant and antiresonant spin carrier transmission. Based on these selection rules and the band shift induced by the magnetic field strength and the tilting angles, we propose an efficient spin inversion device. For a polarized incoming electron beam, we can determine from our theoretical approach, physical conditions for spin-inversion efficiency up to 80%. We visualize this mechanism in terms of conductance and the spacial behavior of the wave function amplitude along the superlattice.Comment: 3 pages, 3 figures, regular pape