Using the covariant spectator theory (CST), I will present results of a valence quark-diquark model
calculation of the nucleon structure function f(x) measured in unpolarized deep inelastic scattering
(DIS), and the structure functions g1(x) and g2(x) measured in DIS using polarized beams and targets.
Parameters of the wave functions are adjusted to fit all the data. The fit fixes both the shape of the
wave functions and the relative strength of each component. Two solutions are found that fit f(x) and
g1(x), but only one of these gives a good description of g2(x). This fit requires the nucleon CST
wave functions contain a large D-wave component (about 35%) and a small P-wave component (about 0.6%).
The significance of these results will be discussed.