Spin force dependence of nucleon structure functions

Abstract

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 $\mu \sim 0.25$ GeV are evolved from (0.6 ${\mathrm{G}\mathrm{e}\mathrm{V})}^2$ to $-q^2\sim 15$ ${\mathrm{GeV}}^2$. 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 $\frac{F_2^n\mathrm{}\left(x\right)\mathrm{}}{F_2^p\mathrm{}\left(x\right)\mathrm{}}$, 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 $A_1^p$ agrees with the EMC data also in the valence quark region.