Estimamos os valores das polarizabilidades dipolares elétrica e magnética do próton, levando em conta as contribuições das ressonâncias nucleônicas de menor massa: P33 (1236), P11 (1450), D13 (1525), S11(1550), e da ressonância mesônica &#949 (660). O valor obtido para a soma das polarizabilidades concorda bem com os dados experimentais. Por outro lado, o valor obtido para cada uma delas, que depende do valor não bem determinado da largura do decaimento &#949 &#8594 &#933 &#933, é compatível com os valores experimentais / We have estimated the values of electric and magnetic polarizabilities of the proton, taking into account the contributions of the low masses nucleon ressonances : P33 (1236), P11 (1450), D13 (1525), S11(1550) and the meson ressonance &#949 (660). The obtained value for the sumo f the polarizabilities is in good agreement with the experimental data. On the other hand, the value, of each polarizability, which depends on the not too well determined width decay &#949 &#8594 &#933 &#933, is compatible with experimental values

Thesis (Ph. D.)--University of Wisconsin--Madison, 1968. / Typescript. Vita. Description based on print version record. Includes bibliographical references.

Estimamos os valores das polarizabilidades dipolares elétrica e magnética do próton, levando em conta as contribuições das ressonâncias nucleônicas de menor massa: P33 (1236), P11 (1450), D13 (1525), S11(1550), e da ressonância mesônica &#949 (660). O valor obtido para a soma das polarizabilidades concorda bem com os dados experimentais. Por outro lado, o valor obtido para cada uma delas, que depende do valor não bem determinado da largura do decaimento &#949 &#8594 &#933 &#933, é compatível com os valores experimentais / We have estimated the values of electric and magnetic polarizabilities of the proton, taking into account the contributions of the low masses nucleon ressonances : P33 (1236), P11 (1450), D13 (1525), S11(1550) and the meson ressonance &#949 (660). The obtained value for the sumo f the polarizabilities is in good agreement with the experimental data. On the other hand, the value, of each polarizability, which depends on the not too well determined width decay &#949 &#8594 &#933 &#933, is compatible with experimental values

Proton Compton scattering has been studied from 220 to 330 MeV at 90 degree center of mass scattering angle with the polarized photon beam at LEGS. Compton scattering is an important probe of the nucleon structure and its excited states. Polarization degrees of freedom reveal more information than unpolarized observables. This experiment measured, for the first time, the polarized cross sections of proton Compton scattering up to the Δ resonance. The parallel and perpendicular cross sections were measured at the same time. All the photons were tagged so that the energy dependent systematic errors are small. The measured unpolarized cross section is above the lower bound from unitary at all energies. The cross section asymmetry is obtained as a function of energy for the first time. The unpolarized cross section is compared with previous data and with calculations from the fixed-t dispersion model, the isobar model and the finite energy dispersion model. Although all these calculations agree fairly well with unpolarized cross section data, the photon asymmetry data show that the isobar model contains serious defects. The ratio of polarized cross sections, dσ_⫫/dσ_⟂, is compared with a model independent result. The results from the present experiment can be used in the calculation of the E2/M1 ratio in the N — Δ transition, which is an important signature of the tensor interaction between quarks. / Ph. D.

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