Mesure d'asymétrie de spin de faisceau en diffusion Compton virtuelle polarisée sur le proton. Etude du spectre d'énergie du nucléon par le modèle de potentiel de type QCD.

Abstract : The first part presents the analysis and result of the VCS-SSA experiment at MAMI (Mainz). It was carried out with beam energy 883 MeV and longitudinal polarization (∼ 80%), at virtual photon four-momentum transfer squared (Q2 =0.35 GeV2)to measure the beam spin asymmetry in the ep → epγ and ep → epπ° reactions. The asymmetry obtained in photon (resp. pion) electroproduction is between 0-15 % (resp. 0-2 %). The Dispersion Relation model for virtual Compton scattering and MAID model (for π°)reproduce the amplitude globally but not completely the shape of the asymmetry. Perhaps this discrepancy is due to an imperfect parameterization of some pion production multipoles (γ(*)N → πN). The second part is dedicated to the study of the nucleon energy spectrum in ground-state L = 0 and excited-state L = 1 in the quark model, using the Coulombian + linear potential type (CL) and a relativistic correction. The hyperfine correction is applied to separate between the nucleon masses. The mass found for the proton and the Δ(1232) is respectively equal to (968 MeV, 1168 MeV), and the masses of the excited states are between 1564 − 1607 MeV. This part is completed by an application of the CL model to an approximate calculation of generalized polarizabilities of the proton.
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Contributor : Jeanine Pellet <>
Submitted on : Friday, June 30, 2006 - 5:49:50 PM
Last modification on : Thursday, January 11, 2018 - 6:14:03 AM
Long-term archiving on : Monday, April 5, 2010 - 11:40:23 PM

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  • HAL Id : tel-00083467, version 1

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I.K. Bensafa. Mesure d'asymétrie de spin de faisceau en diffusion Compton virtuelle polarisée sur le proton. Etude du spectre d'énergie du nucléon par le modèle de potentiel de type QCD.. Physique mathématique [math-ph]. Université Blaise Pascal - Clermont-Ferrand II, 2006. Français. ⟨tel-00083467⟩

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