Spin force dependence of nucleon structure functions

Deep inelastic structure functions for the nucleon are obtained in a constituent quark model on the light cone. In the Bjorken limit the parton model is derived. Structure functions from the hadronic tensor at the scale μ~0.25 GeV are evolved from (0.6 GeV)² to -q²~15 GeV². The model incorporates the quark boosts, is designed to describe form factors and structure functions and to provide a link between the parton and constituent quark models. The main effect of the spin force between quarks is described in terms of smaller (and lighter) scalar u-d quark pairs in the nucleon. To account for the negative slope of F₂ⁿ(x)F₂ᵖ(x), attraction between scalar u-d quark pairs and incorporation of boosts are required. The two-body spin force between quarks from color magnetism leads to a negative slope. The polarization asymmetry A₁ᵖ agrees with the EMC data also in the valence quark region.