Proton structure functions from chiral dynamics and QCD constraints

The spin fractions and deep inelastic lepton structure functions of the proton are analyzed based on chiral field theory involving Goldstone bosons. A detailed comparison with several recent chiral models sheds light on their successful description of the spin fractions of the proton as being due to neglecting quark masses. Initial quark valence distributions at a higher scale than Lambda(QCD) are constructed using quark counting constraints at large Bjorken x --> 1 and Regge behavior at small x. Reasonable strange quark distributions are then predicted by chiral field theory. The spin fractions also agree with the data.