259 resultados para GLUON CONDENSATE
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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We study the production of charmed mesons (D) and baryons (Lambda(c)) in antiproton- proton ((p) over barp) annihilation close to their respective production thresholds. The elementary charm production process is described by either baryon/ meson exchange or by quark/ gluon dynamics. Effects of the interactions in the initial and final states are taken into account rigorously. The calculations are performed in close analogy to our earlier study on (p) over bar -> (Lambda) over bar Lambda and (p) over barp (K) over bar K by connecting the processes via SU(4) flavor symmetry. Our predictions for the (Lambda) over bar (c)Lambda(c) production cross section are in the order of 1 to 7 mb, i. e. a factor of around 10-70 smaller than the corresponding cross sections for (Lambda) over bar Lambda However, they are 100 to 1000 times larger than predictions of other model calculations in the literature. on the other hand, the resulting cross sections for (D) over barD production are found to be in the order of 10(-2) - 10(-1)mu b and they turned out to be comparable to those obtained in other studies.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Using the complete numerical solution of a time-dependent three-dimensional rnean-field model we study the Josephson oscillation of a superfluid Fermi gas (SFG) at zero temperature formed in a combined axially-symmetric harmonic plus one-dimensional periodic optical-lattice (OL) potentials after displacing the harmonic trap along the axial OL axis. We study the dependence of Josephson frequency on the strength of the OL potential. The Josephson frequency decreases with increasing strength as found in the experiment of Cataliotti et al. [Science 293, 843 (2001)] for a Bose-Einstein condensate and of the experiment of Pezze et al. [Phys. Rev. Lett. 93, 120401 (2004)] for an ideal Fermi gas. We demonstrate a breakdown of Josephson oscillation in the SFG for a large displacement of the harmonic trap. These features of Josephson oscillation of a SFG can be tested experimentally.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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We study the low-energy scattering of charmed (D) and strange (K) mesons by nucleons. The short-distance part of the interaction is due to quark-gluon interchanges derived from a model that realizes dynamical chiral symmetry breaking and confines color. The quark-gluon interaction incorporates a confining Coulomb-like potential extracted from lattice QCD simulations in Coulomb gauge and a transverse hyperfine interaction consistent with a finite gluon propagator in the infrared. The long-distance part of the interaction is due to single vector (rho, omega) and scalar (sigma) meson exchanges. We show results for scattering cross-sections for isospin I = 0 and I = 1.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)