Physics Diploma Thesis: Exploration of different confinement and hyperfine interactions in a constituent quark model for baryons
Reinhold Kainhofer, January 2003
Abstract
In this work we investigate the spectra of light and strange baryons for different effective interactions between constituent quarks. In particular we examine the influence of an additional Coulomb term on top of a linear confinement and variants of the hyperfine interactions derived from Goldstone-boson-exchange (GBE) dynamics; the latter include specifically pseudoscalar, vector and scalar exchanges. We present our own parametrization of an extended GBE constituent quark model (CQM) with all but spin-orbit forces included. The resulting spectra produce most states to a high accuracy, and the correct level orderings in the nucleon, $\Lambda$ and $\Sigma$ spectra can be obtained.
The only remaining problems are the states N(1680) and N(1675), which cannot be described in accordance with their almost degeneracy observed in experiment, and the Lambda(1405), which is obviously much influenced by the nearby KN threshold and can probably not be explained by a constituent quark model relying on {QQQ} configurations only.
The version of the extended GBE CQM constructed here is mainly intended to serve as a basis for the inclusion of the missing spin-orbit terms of the meson-exchange potentials, which is the central subject matter in a parallel diploma work.
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