Models for the Polarized Parton Distributions of the Nucleon

Polarized deep inelastic scattering (DIS) data are analyzed in leading and next–to– leading order of QCD within the common ‘standard’ scenario of polarized parton distributions with a flavor–symmetric light sea (antiquark) distribution δq̄, and a completely SU(3)f broken ‘valence’ scenario with totally flavor-asymmetric light sea densities (δū 6= δd̄ 6= δs̄). The latter flavor–broken light sea distributions are modelled with the help of a Pauli–blocking ansatz at the low radiative/dynamical input scales of μLO(NLO) = 0.26 (0.40) GeV 2 which complies with predictions of the chiral quark–soliton model and expectations based on the statistical parton model as well as with the corresponding, well established, flavor–broken unpolarized sea (d̄ > ū). Present semi–inclusive DIS data cannot yet uniquely discriminate between those two flavor–symmetric and flavor–broken polarized light sea scenarios.