Orientador: Adriano Antonio Natale / Banca: Atílio Cucchieri / Banca: Márcio José Menon / Banca: Maria Beatriz de Leone Gay Ducati / Banca: Rogério Rosenfeld / Resumo: Através da solução das equações de Schwinger-Dyson (ESD) é possível estudar diversos aspectos importantes da QCD não-perturbativa como confinamento e quebra de simetria quiral; desta forma as ESD são, obviamente, muito interessantes para estudo da fenomenologia das interações hadrônicas. Após uma breve revisão sobre equações de Schwinger-Dyson (ESD) e sobre algumas soluções da ESD do propagador do glúon disponíveis na literatura, apresentamos possíveis testes fenomenológicos para estas soluções. Observaremos que apenas uma das soluções apresentadas descreve satisfatoriamente os dados experimentais, e esta solução é compatível com uma massa dinâmica para o glúon. Finalizando, supomos que o glúon têm uma massa dinâmica e calculamos seus efeitos sobre os decaimentos de quarkônios pesados / Abstract: Through the solution of Schwinger-Dyson equations (SDE) it is possible to study important features of nonperturbative QCD such as confinement and chiral symmetry breaking; in this way SDE are, obviously, very interesting for the study of phenomenology of hadronic interactions. After a brief review on SDE and some Solutions of gluon propagator SDE available in literature, we present possible phenomenological tests for these solutions. We shall observe that only one of the solutions presented describes satisfactorily the experimental data, and such solution is compatible with a dynamical mass for the gluon. Eventually, we assume that the gluon has a dynamical mass and calculate its effects on heavy quarkonia decays / Doutor

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Unexpected properties of recently discovered mesons DsJ(2317) and DsJ(2460) have caused an excitement in the high energy community. These mesons are under experimental study in BaBar, Belle and CLEO. The experimental data on these mesons is quite limited at the moment, but it is expected to be improved in the following years. The unexpected properties of these mesons, such as the low mass, and small width, have caused speculations about their structure. Various models have been proposed which go beyond the simple quark-antiquark picture of the mesons, such as a meson molecule, or a four-quark state. Therefore, understanding the underlying structure of these mesons can reveal a deeper understanding of QCD. In this thesis, the strong decay of the DsJ(2317) meson, DsJ(2317)--&gt / Dspi0, is studied using three-point QCD Sum Rules method in the conventional cs framework. DsJ(2317) -&gt / Dspi0 decay violates isospin symmetry. Therefore, this decay is studied as a two stage process / an isospin conserving DsJ(2317) --&gt / Ds eta decay followed by the conversion of eta into a pi0 due to isospin violation.

<p>Quantum chromodynamics (QCD), the theory of quarks and gluons, is known to be</p><p>the correct description of strong nuclear interactions. At high energy and momenta,</p><p>one can use QCD directly to compute quantities of physical interest related to the</p><p>strong force. At low energies and momenta, one should use a different description in</p><p>terms of the degrees of freedom relevant at that scale. Two approaches to achieve</p><p>this end are effective field theories and gauge/gravity dualities. The former involves</p><p>a field theory more or less like QCD itself, but with states which are composites</p><p>of quarks and gluons. Then a perturbative expansion is made not in terms of the</p><p>gauge coupling but instead in terms of the momentum of the fields. This approach</p><p>dates back to the 1970s and is on firm theoretical footing. Gauge/gravity dualities</p><p>are a newer and less understood technique, which relates the physics of the strong</p><p>interactions to a different but likely equivalent theory in a higher dimensional space-</p><p>time, where the quantity of interest can be computed more readily. We employ</p><p>both effective field theories and gauge/gravity dualities to study the physics of ex-</p><p>otic quarkonium states, that is bound states containing a heavy quark-antiquark pair</p><p>which nevertheless cannot be be understood working only with the standard quark</p><p>model of hadrons. Candidates for such states, long speculated to exist, have recently</p><p>been observed at particle colliders, so that the theory of exotic quarkonium is now</p><p>of great experimental importance.</p> / Dissertation

Thesis (M.S.)--Mississippi State University. Department of Physics and Astronomy. / Title from title screen. Includes bibliographical references.

A representação de Fock-Tani é um formalismo de teoria de campos apropriado para o tratamento simultâneo de partículas compostas e seus constituintes. O modelo 3P0 é um típico modelo de decaimento que considera somente decaimentos fortes do tipo OZI-permitidos. O modelo considera um par quark-antiquark criado com os números quânticos do vácuo na presença do méson do estado inicial. Ele é descrito pelo limite não relativístico do Hamiltoniano de criação de par. Aplicando a transformação de Fock-Tani ao Hamiltoniano microscópico de criação de par produz-se a expansão caraterística em potências da função de onda, onde o modelo 3P0 ´e a ordem mais baixa desta expansão. O modelo 3P0 corrigido (C3P0) é obtido em mais altas ordens nesta expansão, pela introdução do kernel de estado ligado ¢, chamado de correção de estado ligado. O objetivo deste trabalho é estudar em detalhe o setor de mésons charmosos (mésons D) e o setor de mésons charmosos-estranhos (mésons DSJ ) usando o modelo C3P0, onde o modelo C3P0 é expandido com a inclusão da segunda ordem da correção de estado ligado pelo método diagramático. Em particular, obtemos as amplitudes e taxas de decaimento dos seguintes canais: Setor charmoso e Setor charmoso-estranho. / The Fock-Tani representation is a field theory formalism appropriated for the simultaneous treatment of composite particles and their constituents. The 3P0 model is a typical decay model which considers only OZI-allowed strong decays. The model considers a quark-antiquark pair created with the vacuum quantum numbers in the presence of the initial state meson. It is described as the non-relativistic limit of the pair creation Hamiltonian. Applying the Fock-Tani transformation to the microscopic Hamiltonian of the pair creation produces the characteristic expansion in powers of the wave function, where the 3P0 model is the lowest order in the expansion. The corrected 3P0 model (C3P0) is obtained from higher orders in the expansion, by the introduction of the bound state kernel ¢, called the bound state correction. The goal of this work is to study in detail the charmed meson sector (D meson) and the strange charmed meson sector (DSJ meson) using the C3P0 model, where the C3P0 model is expanded by the inclusion of the second order of the bound state correction for the diagramatic method. In particular, we shall calculate the decay amplitudes and decay rates of the following channels: Charmed sector and Strange charmed sector.