Deep Inelastic Scattering Structure Functions of the Nucleon in Quark Models

The connection between the structure functions of a free nucleon measured in deep inelastic scattering (DIS) experiments and the underlying dynamics in the nucleon rest frame in quark models is not well understood. This thesis explores some steps towards improving the theory of nucleon structure functions. The polarized spin structure functions are calculated in the Fermi gas model. The model permits a straightforward calculation in a translationally invariant framework and demonstrates the importance of relativistic kinematics for spin structure functions. The effect of interactions on the leading light-cone singularity of quark fields has been studied in an exactly solvable bound state model. Using the standard paradigm for calculating structure functions in quark models it is found that the leading light-cone singularity differs from that of free field theory. A fully relativistic proton state with good Poincare symmetry is constructed and it is used to study the proton spin structure in DIS experiments. We find that due to internal motion of quarks the u quark occupation number matrix is rotated by a Wigner rotation, and thus the u quark occupation number is not diagonal in the nucleon rest frame. We also observe that the flavor singlet axial charge DeltaSigma (i.e. Delta u + Delta d + Delta s) is not unity even though the implications of quantum chromodynamics (QCD) such as the U(1) axial anomaly are irrelevant in our model.