Efeito da troca de um méson sigma no decaimento hipernuclear fraco não-mesônico

• Ano de defesa: 2007
• Autor(a) principal: Fontoura, Carlos Eduardo [UNESP]
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Estadual Paulista (Unesp)
• Palavras-chave em Português: Nuclear physics; Física nuclear
• Link de acesso: http://hdl.handle.net/11449/154678; http://www.athena.biblioteca.unesp.br/exlibris/bd/cathedra/01-11-2017/000722927.pdf

In this work we investigate the influence of the exchange of a scalar-isoscalar sigma meson on some of the main observables in the nonmesonic hypernuclear weak decay. We discuss in detal the formalism based on the extreme shell model for the computation of the nonmesonic weak decay rates. The weak transition potential for the strangeness changing ('delta'S =1) process 'lâmbda'nü' 'SETA'nü'nü' is constructed based on several one-meson-exchange models, that include, beyond of the pseudoscalar ('pi', 'capa', 'eta') and the vector ('rô', 'ômega', 'capa'*) mesons, a ew contribution due to the scalar-isoscalar 'sigma' meson. We also present the numerical results obtained for the total nonmesonic rate, 'gama IND. nm='gama IND.n' + 'gama IND. p', and for the ration 'gama IND. n'/'gama IND. p' in the decay of 'INTPOT. 5 ANTIND. 'LÂMBDA' He'. We show that the influence of the 'sigma' meson is significant and goes in the direction of increasing the 'gama IND. n'/'gama IND. p'ratio.