Thesis--University of California, Berkeley, 1961. / "UC-34 Physics" -t.p. "TID-4500 (16th Ed.)" -t.p. Errata sheet at end. Includes bibliographical references (p. 39-40).

Thesis--University of California, Berkeley, 1963. / "UC-34 Physics" -t.p. "TID-4500 (19th Ed.)" -t.p. Includes bibliographical references (p. 75-77).

Thesis (Ph.D.)--University of California, Berkeley, 1963. / "UC-34 Physics" -t.p. "TID-4500 (19th Ed.)" -t.p. Includes bibliographical references (p. 95-97).

Thesis (Ph. D.)--University of Chicago, Dept. of Physics, March 2003. / Includes bibliographical references. Also available on the Internet.

Made available in DSpace on 2016-01-13T13:27:34Z (GMT). No. of bitstreams: 0 Previous issue date: 1994. Added 1 bitstream(s) on 2016-01-13T13:33:01Z : No. of bitstreams: 1 000524316.pdf: 3132245 bytes, checksum: cdfd47a27f819ee95d467ba02ef476d7 (MD5) / Este trabalho consiste no estudo do papel das simetrias quiral e de calibre eletromagnético, da constante 'g IND. A' e do tipo de acoplamento pion-núcleon em três processos: fotoprodução de um píon e de dois píons e interação fóton-núcleon. Os dois primeiros processos são tratados na aproximação em árvore, enquanto que no último são considerados também diagramas envolvendo um loop. O papel das simetrias é analisado investigando-se a existência de relações entre os vários diagramas de um dado processo. Já o papel do tipo de acoplamento pion-núcleon é analisado, comparando-se os resultados obtidos por meio de dois modelos de implementação da simetria quiral: o sigma linear e o não linear de Weinberg. Analogamente, o papel de 'g IND. A' é avaliado pela inspeção direta das expressões obtidas para os vários processos. Este estudo mostrou que, apenas no processo envolvendo dois píons externos a simetria quiral é relevante. Em particular, a simetria quiral é irrelevante para o fator de forma eletromagnético devido à nuvem piônica do núcleon, pelo menos no contexto das correções de um loop consideradas. Estes resultados constituem pontos de partida para o estudo mais abrangente do papel da simetria quiral em abordagens não perturbativas, tais como a do modelo de Skyrme / In this Work we study the role played by chiral and electromagnetic gauge symmetries, the weak constant 'g IND. A' and pion-nucleon couplings in three processes; single and double pion photo production and photon-nucleon interaction. The first two of them are treated at tree levei, whereas the last one includes one loop corrections. The role of the symmetries is analyzed considering the existence of relationships among various diagrams contributing to a given process. The influence of the way pions couple to nucleons is studied by comparing results obtained by means of the linear sigma model and the non linear model proposed by Weinberg. Finally, the role of 'g IND. A' is assessed by direct inspection of formal expressions. Our study showed that chiral symmetry is relevant only for double pion photo production. In particular, chiral symmetry does not influence the pion cloud contribution to the electromagnetic nucleon form factor, at least within the one loop approximation considered. These results pave the way for more comprehensive studies of the role of chiral symmetry in non perturbative approaches, such as the Skyrme model

Orientador: Manoel Roberto Robilotta / Banca: Fernando Silveira Navarro / Banca: Bruto Max Pimentel Escobar / Resumo: Este trabalho consiste no estudo do papel das simetrias quiral e de calibre eletromagnético, da constante 'g IND. A' e do tipo de acoplamento pion-núcleon em três processos: fotoprodução de um píon e de dois píons e interação fóton-núcleon. Os dois primeiros processos são tratados na aproximação em árvore, enquanto que no último são considerados também diagramas envolvendo um loop. O papel das simetrias é analisado investigando-se a existência de relações entre os vários diagramas de um dado processo. Já o papel do tipo de acoplamento pion-núcleon é analisado, comparando-se os resultados obtidos por meio de dois modelos de implementação da simetria quiral: o sigma linear e o não linear de Weinberg. Analogamente, o papel de 'g IND. A' é avaliado pela inspeção direta das expressões obtidas para os vários processos. Este estudo mostrou que, apenas no processo envolvendo dois píons externos a simetria quiral é relevante. Em particular, a simetria quiral é irrelevante para o fator de forma eletromagnético devido à nuvem piônica do núcleon, pelo menos no contexto das correções de um loop consideradas. Estes resultados constituem pontos de partida para o estudo mais abrangente do papel da simetria quiral em abordagens não perturbativas, tais como a do modelo de Skyrme / Abstract: In this Work we study the role played by chiral and electromagnetic gauge symmetries, the weak constant 'g IND. A' and pion-nucleon couplings in three processes; single and double pion photo production and photon-nucleon interaction. The first two of them are treated at tree levei, whereas the last one includes one loop corrections. The role of the symmetries is analyzed considering the existence of relationships among various diagrams contributing to a given process. The influence of the way pions couple to nucleons is studied by comparing results obtained by means of the linear sigma model and the non linear model proposed by Weinberg. Finally, the role of 'g IND. A' is assessed by direct inspection of formal expressions. Our study showed that chiral symmetry is relevant only for double pion photo production. In particular, chiral symmetry does not influence the pion cloud contribution to the electromagnetic nucleon form factor, at least within the one loop approximation considered. These results pave the way for more comprehensive studies of the role of chiral symmetry in non perturbative approaches, such as the Skyrme model / Mestre

Submitted by Marcele Costal de Castro (costalcastro@gmail.com) on 2017-09-27T16:16:04Z No. of bitstreams: 1 GONÇALO RODRIGUES DOS SANTOS M.pdf: 1459969 bytes, checksum: 8b3fc490a0a359784ab9aa180749a587 (MD5) / Made available in DSpace on 2017-09-27T16:16:04Z (GMT). No. of bitstreams: 1 GONÇALO RODRIGUES DOS SANTOS M.pdf: 1459969 bytes, checksum: 8b3fc490a0a359784ab9aa180749a587 (MD5) Previous issue date: 1982-11 / Estudamos a amplitude de desintegração y → 3π usando o método de pions duros da álgebra de correntes baseado na técnica das identidades de Ward do grupo quiral SU (2) XSU (2). Este método conduziu a uma expressão geral relacionando os processos y → 3π c π°→ 2y que possibilita reobter, no limite de pions moles, a relação de Adler e introduzir nela correções através do propagador vetorial e do fator de forma eletromagnético do pion.

No description available.

A partial-wave analysis of pion photoproduction data up to a photon lab energy of 1.8 GeV has been performed. Both energy-dependent and energy-independent solutions have been obtained. The energy-dependent parametrization incorporates the recently determined elastic pion nucleon scattering amplitudes in such a way as to satisfy unitarity and utilize the resonance structure contained in the pion nucleon elastic amplitudes. Starting from the energy-dependent solution, energy-independent partial-wave solutions are obtained at a set of energies from threshold to 1.8 GeV. The data base used in the analysis contains 11,911 data from the reactions. The predictions of our solution are compared with the experimental data and previous analyses. Suggestions are made for future experiments. A total of sixteen resonances exist in the energy range from threshold to 1.8 GeV. These resonance states are studied using our energy-independent solutions. Photon decay couplings to the sixteen resonances are extracted. These couplings are also compared with previous solutions and quark model predictions. / Ph. D.

The Monte Carlo method has been utilized to determine a procedure for the simulation of π° production near threshold. A number of computer programs have been written to perform as well as test the simulation process. The method consists of generating the pion angles in the center of mass frame and subsequently its decay gammas in the lab frame of the reaction. The gamma distribution generated is fitted via the method of maximum likelihood, and the angular distribution parameters are compared to those utilized in the generation process. Due to an ambiguity in the normalization of the parameters, the ratios of the parameters are considered instead of their absolute magnitude. The fitted parameters are found to agree with the parameters used in the generation program within the limits expected from statistical theory. / Master of Science