Qcd Sum Rules
Mostrando 1-12 de 15 artigos, teses e dissertações.
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1. Estrutura dos estados exóticos do charmônio utilizando as regras de soma da QCD / Structure of the exotic states of the charmonium spectrum using the QCD sum rules
Recentemente, a colaboração CDF encontrou evidência para uma nova ressonância do tipo do charmônio no espectro de massa invariante do decaimento $B^{\\pm} ightarrow K^{\\pm} J/\\psi \\phi$. Esta ressonância tem uma massa de $4274.4^{+8.4}_{-6.7} \\, \\mathrm(estat) \\, \\pm 1.9 (sist) \\, \\mathrm$ - recebendo, portanto, o nome de Y(4274) - e largura t
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 02/02/2012
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2. O vértice D*Dp usando as regras de soma da QCD / The D*Dp vertex using the QCD sum rules
The particle physics have been studying topics like the Quark-Gluon Plasma (QGP), Higgs boson and dark matter, which require experiments in heavy-ion collisions. Therefore, accelerators capable of generate high energy particle beams are necessary and may generate new physics. When new data arise in the laboratories, new processes are necessary to explain thi
Publicado em: 2010
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3. Study of the structure of new mesons / Estudo da estrutura dos novos mésons
We use QCD sum rules to test the nature of the recently observed mesons Y (4260), Y (4360) and Y (4660), assumed to be exotic four-quark (c¯cq¯q) or (c¯cs¯s) states with JPC = 1. We work at leading order in s, consider the contributions of higher dimension condensates and keep terms which are linear in the strange quark mass ms. We find for the (c¯cs¯s
Publicado em: 2009
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4. Thermal properties of heavy-light quark pseudoscalar and vector mesons
The thermal behaviour of the mass, leptonic decay constant, and width of heavy-light quark peseudoscalar and vector mesons is analized in the framework of thermal Hilbert moment QCD sum rules. In all the cases, the meson leptonic decay constants decrease with increasing T, and vanish at a critical temperature Tc, while the mesons develop a width which increa
Brazilian Journal of Physics. Publicado em: 2008-09
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5. Charmed scalar mesons masses within the QCD sum rules framework
In this work, we evaluate the D+sJ(2317), D(0)0(2308), D(0)0(2407) and D+0(2403) masses. These are scalar mesons recently discovered in the BABAR, BELLE and FOCUS Collaborations. The nature of these particles is intensely discussed nowadays. We treat them as a diquark-antidiquark configuration and treat the problem using the QCD sum rules (QCDSR) approach.
Brazilian Journal of Physics. Publicado em: 2007-03
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6. X (3872) in QCD sum rules
QCD spectral sum rules is used to test the nature of the meson X(3872), assumed to be an exotic four-quark $(c\bar{c}q\bar{q})$ state with J PC = 1++. For definiteness, the current proposed recently by Maiani et al [1] is used, at leading order in alphas, considering the contributions of higher dimension condensates. The value M X = (3.94±0.11) GeV is found
Brazilian Journal of Physics. Publicado em: 2007-03
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7. Coupling constants of D*DsK and Ds*DK processes
We calculate the coupling constants of D*Ds K and Ds*DK vertices using the QCD sum rules technique. We compare our results with results obtained in the limit of SU(4) symmetry and we found that the symmetry is broken at the order of 40%.
Brazilian Journal of Physics. Publicado em: 2007-03
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8. Rise and fall of pentaquarks in the QCD Sum Rules approach
We review the existing mass and decay width determinations of pentaquarks with QCD Sum Rules (QCDSR). We give special attention to the intermediate assumptions and choices which we are obliged to do in this approach. As an example, we present the full calculation of the pentaquark mass with Borel sum rules and also with Finite Energy Sum Rules (FESR). We als
Brazilian Journal of Physics. Publicado em: 2006-12
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9. 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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10. 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
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11. Topological charge screening and pseudoscalar glueballs
Topological charge screening in the QCD vacuum is found to provide crucial nonperturbative contributions to the short-distance expansion of the pseudoscalar (0-+) glueball correlator. The screening contributions enter the Wilson coefficients and are an indispensable complement to the direct instanton contributions. They restore consistency with the anomalous
Brazilian Journal of Physics. Publicado em: 2004-09
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12. J/psiD*D* form factor from QCD sum rules
We calculate the J/psiD*D* form factor and coupling constant from QCD Sum Rules in the cases where J/psi and D* mesons are off-shell. The results show that this method is consistent and allows to extract the same coupling constant for the vertex.
Brazilian Journal of Physics. Publicado em: 2004-03