240 research outputs found
Glueball-glueball scattering in a constituent gluon model
In this work we use a mapping technique to derive in the context of a
constituent gluon model an effective Hamiltonian that involves explicit gluon
degrees of freedom. We study glueballs with two gluons using the Fock-Tani
formalism. In the present work we consider two possibilities for : (i)
as a pure and calculate, in the context of a quark interchange
picture, the cross-section; (ii) as a glueball where a new calculation for this
cross-section is made, in the context of the constituent gluon model, with
gluon interchange.Comment: Proceedings of the International Workshop IX Hadron Physics and VII
Relativistic Aspects of Nuclear Physics (HADRON-RANP 2004
Meson decay in the Fock-Tani Formalism
The Fock-Tani formalism is a first principle method to obtain effective
interactions from microscopic Hamiltonians. Usually this formalism was applied
to scattering, here we introduced it to calculate partial decay widths for
mesons.Comment: Presented at HADRON05 XI. "International Conference on Hadron
Spectroscopy" Rio de Janeiro, Brazil, August 21 to 26, 200
Glueball-glueball potential in a constituent gluon model
In this work we use a mapping technique to derive in the context of a
constituent gluon model an effective Hamiltonian that involves explicit gluon
degrees of freedom. We study glueballs with two gluons using the Fock-Tani
formalism. In the present work we calculate the glueball-glueball potential, in
the context of the constituent gluon model, with gluon interchange.Comment: 5 pages, 2 figures, talk by M. L. L. da Silva at IWARA Meeting,
October 2011, Joao Pessoa, Brazil. Version to be published in International
Journal of Modern Physics: Conference Serie
Atividade da reductase do nitrato em milho (Zea mays L.) var. PiranĂŁo em nĂveis crescentes de nitrogĂȘnio.
O objetivo deste trabalho foi estudar a atividade da reductase do nitrato em milho (Zea mays L. var. "Piranao") cultivado em solucao nutritiva e sob doses crescentes de nitrogenio, na forma de NO3. A atividade da enzima foi analisada aos 56 dias de idade, em rodelas de folhas do terco medio da folha +4, seguindo-se a metodologia proposta por MULDER et alii (15), adaptada por MALAVOLTA (13). Os resultados permitiram concluir que o aumento do teor de NO3 no meio favoreceu a atividade da reductase do nitrato ate o nivel maximo de 40,51 ug de N-NO-2/g de materia verde, correspondente a um nivel de 296,19 mg de N/litro de solucao nutritiva. Os resultados obtidos nas condicoes experimentais em que foi realizado o trabalho correspondem, provavelmente, ao maximo da capacidade genetica da variedade estudada. Os teores de N encontrados nas folhas inferiores foram mais baixos do que os das folhas superiores, em funcao da alta mobilizacao do elemento para as partes mais novas da planta. Houve tambem correlacao positiva entre a atividade da reductase do nitrato, o teor de N total da folha e a producao de materia seca
Quark Model Estimates of the Structure of the Meson-N-N*(1535,1/2-) Transition Vertices
We address an actual problem of baryon-resonance dominated meson-exchange
processes in the low GeV regime, i.e. the phase and the structure of meson-NN*
transition vertices. Our starting point is a quark-diquark model for the
baryons (obeying approximate covariance; the mesons are kept as elementary
objects), together with the relative phases for the NN vertices, as determined
from low energy NN scattering. From the explicit representation of the N and N*
baryons, we exemplify the derivation of the coupling constants and form factors
of the NN*(1535,1/2-)transition vertices for pseudo-scalar, scalar and vector
mesons.Comment: 17 pages, 5 figures, 1 tabl
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