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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Simetria quiral, modelos de quarks e espalhamento píon-píon no formalismo fock-tani /

Manzoni, Luiz ALberto. January 1995 (has links)
Orientador: Gastão Inácio Krein / Banca: Vicente Pleitez / Banca: Manoel Roberto Robilotta / Resumo: Consideramos modelos de quarks quirais para estudar o espalhamento 'PI-PI' a baixas energias. A quebra dinâmica da simetria quiral é estudada através do método variacional de Bogoliubov-Valatin. Dentro deste esquema, a estrutura de quarks dos pions considerados como bosons de Goldstone é obtida. Através do formalismo Fock-Tani obtemos um Hamiltoniano efetivo em termos dos graus de liberdade piônicos e a partir deste obtemos a amplitude de espalhamento 'PI-PI' no limiar. Usando a propriedade de "crossing" da matriz de espalhamento, o resultado é estendido para energias além do limiar. O resultado concorda com aquele obtido por Weinberg no contexto da álgebra de correntes / Abstract: We consider chiral quark models to study 'PI-PI' scattering at low energies. The dynamical chiral symmetry breaking is studied by means of the Bogoliubov-Valatin variational method. Within such a scheme, the quark structure of the pions considered as Goldstone bosons is obtained. By means of the Fock-Tani formalism we obtain an effective Hamiltonian in terms of pion degrees of freedom and from this we obtain the 'PI-PI' scattering matrix at threshold. Using the crossing property of the scattering matrix, the result is extended to energies beyond threshold. The result agrees with the one obtained by Weinberg in context of current algebra / Mestre

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