Qcd Model
Mostrando 13-24 de 34 artigos, teses e dissertações.
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13. Charmed-meson scattering on nucleons in a QCD Coulomb gauge quark model
The scattering of charmed mesons on nucleons is investigated within a chiral quark model inspired on the QCD Hamiltonian in Coulomb gauge. The microscopic model incorporates a longitudinal Coulomb confining interaction derived from a self-consistent quasi-particle approximation to the QCD vacuum, and a traverse hyperfine interaction motivated from lattice si
Brazilian Journal of Physics. Publicado em: 2007-03
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14. Hydrodynamic evolution near QCD critical point
Some consequences of the presence of critical point in the equation of state on the hydrodynamical evolution of the strongly interacting matter are discussed. For this purpose, we apply the low energy effective theory of QCD, the Nambu-Jona-Lasinio model and show some examples.
Brazilian Journal of Physics. Publicado em: 2007-03
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15. Connecting an effective model of confinement and chiral symmetry to lattice QCD
We construct an effective model for the chiral field and the Polyakov loop in which we can investigate the interplay between the approximate chiral symmetry restoration and the deconfinement of color in a thermal SU(3) gauge theory with three flavors of massive quarks. The phenomenological couplings between these two sectors can then be related to the recent
Brazilian Journal of Physics. Publicado em: 2007-03
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16. Cold and dense perturbative Yukawa theory with massive fermions
Recent results for the two-loop thermodynamic potential of QCD at finite density have shown that nonzero quark mass corrections to the pressure are relevant and can dramatically affect the structure of compact stars. Motivated by these findings, we consider a simple toy model - cold and dense Yukawa theory - to study the effects of finite fermion masses on t
Brazilian Journal of Physics. Publicado em: 2007-03
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17. Linear sigma model at finite baryonic density and symmetry breakings
The linear sigma model at finite baryonic density with a massive vector field is investigated considering that all the bosonic fields develop non zero expected classical values, eventually associated with condensates and corresponding to dynamical symmetry breakings which might occur in the QCD phase diagram. A modified equation for the classical vector fiel
Brazilian Journal of Physics. Publicado em: 2007-03
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18. Meson loops and the gD*Dpi coupling
The D*Dpi form factor is evaluated at low and moderate Q² in a hadronic loop model, for off-shell D mesons. The results contain arbitrary constants, which are fixed so as to match a previous QCD sum rule calculation valid at higher Q². The form factor obtained in this way is used to extract the coupling constant, which is in very good agreement with the ex
Brazilian Journal of Physics. Publicado em: 2006-12
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19. Chasing the Unicorn: RHIC and the QGP
At nonzero temperature, it is expected that QCD undergoes a phase transition to a deconfined, chirally symmetric phase, the Quark-Gluon Plasma (QGP). I review what we expect theoretically about this possible transition, and what we have learned from heavy ion experiments at RHIC. I argue that while there are unambiguous signals for qualitatively new behavior
Brazilian Journal of Physics. Publicado em: 2006-03
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20. Exotic Hadrons in a QCD Sum Rules calculation / "Partículas exóticas em regras de soma da QCD"
In this work the QCD Sum Rules have been used to obtain masses and coupling or decay constants of the theta+(1540) and cascade--(1862) pentaquarks, the DsJ+(2317), D0(2308) and D0(2405) charmed scalar mesons and the X(3872) axial meson. The mesons have been treated as 4-quark exotic states (tetraquarks). Two sum rules methods have been used with special atte
Publicado em: 2006
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21. Quark matter in a QCD Coulomb gauge quark model
In this communication we present results of a study of chiral symmetry in quark matter using an effective Coulomb gauge QCD Hamiltonian. QCD in Coulomb gauge is convenient for a variational approach based on a quasiparticle picture for the transverse gluons, in which a confining Coulomb potential arises naturally. We show that such an effective Hamiltonian p
Brazilian Journal of Physics. Publicado em: 2005-09
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22. 3S1 and ¹S0 meson spectra in a renormalized QCD-inspired model
In this work we study an extension of a light-cone QCD-inspired model, where the interacting part of the mass squared operator consists of a harmonic oscillator potential as confinement, a Coulomb-like interaction and a zero-range spin interaction acting on the ³S0 states. The renormalization of the model is performed by using as a input the pion mass to fi
Brazilian Journal of Physics. Publicado em: 2005-09
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23. Topics on high-energy elastic hadron scattering
We review the main results we have obtained in the area of high-energy elastic hadron scattering and presented in this series of Workshops on Hadron Interactions. After an introduction to some basic experimental and theoretical concepts, we survey the results reached by means of four approaches: analytic models, model-independent analyses, eikonal models and
Brazilian Journal of Physics. Publicado em: 2005-03
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24. The coupling constants in QCD sum rules / "Constantes de acoplamento a partir das regras de soma da QCD"
We use the QCD sum rules to obtain the masses of the pentaquarks _+(1540) and _−−(1862), _+ decay width and the coupling constant and the form factor for the J/ DD* vertex.In the study of the pentaquarks, we use two kinds of interpolating fields, containing two highly correlated diquarks. We get the masses in a good agreement with the experimenta
Publicado em: 2005