UBC Theses and Dissertations
The cloudy bag model Théberge, Serge
In this thesis, a new model for the internal structure of baryons, the Cloudy Bag Model (CBM), is presented. The baryons are assumed to be made of quarks permanently confined in a static spherical cavity called the "Bag", and of a cloud of pions which couple to the quarks at the bag surface in a way which restores chiral symmetry. When the CBM Lagrangian density is projected on the space of colourless baryons, a Hamiltonian theory of baryons coupled to pions is obtained. The model describes successfully the P₃₃ resonance in pion-nucleon scattering, the magnetic moments of the baryon octet and the charge radii of the nucleon. All these results agree rather well with experiment when the only true free parameter of the theory, the bag radius, is chosen anywhere in the range 0.8 to 1.1 fermi.
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