Nucleon Structure Functions within a Chiral Soliton Model ∗

We study nucleon structure functions within the bosonized Nambu–Jona–Lasinio model where the nucleon emerges as a chiral soliton. We discuss the model predictions on the Gottfried sum rule for electron–nucleon scattering. A comparison with a low–scale parametrization shows that the model reproduces the gross features of the empirical structure functions. We also compute the leading twist contributions of the polarized structure functions g 1 and g 2 in this model. We compare the model predictions on these structure functions with data from the E143 experiment by GLAP evolving them appropriately. Here we discuss a possible link between two successful although seemingly unrelated pictures of baryons. On one side the quark parton model successfully describes the scaling behavior of the structure functions in deep inelastic scattering (DIS) processes. Scaling violations are computed within perturbative QCD. On the other side the chiral soliton approach, motivated by the large N C (number of colors) expansion of QCD, gives a fair account of many static baryon properties. For N C → ∞, QCD is equivalent to an effective theory of weakly interacting mesons. This unknown meson theory is modeled by rebuilding the symmetry structure of QCD. In particular this concerns chiral symmetry and its spontaneous breaking. Baryons then emerge as non–perturbative (topological) meson fields configurations, the so–called solitons. It is our goal to link these two pictures by computing nucleon structure functions within a chiral soliton model. We start from the hadronic tensor W ab µν (q) =