Spin and flavor dependent parton distribution and fragmentation functions for octet baryons

I discuss the quark parton structure of octet baryons and the fragmentation of quarks into baryons in a spectator diquark model. The hyperfine interaction, responsible for the ∆-N and Σ-Λ mass splittings, leads not only to sizable SU(3) and SU(6) symmetry breaking in the quark distributions among the octet baryons but also to significant polarized non-strange quark distributions for the Λ. The same arguments suggest flavor asymmetric quark fragmentation functions for the octet baryons and non-zero polarized non-strange quark fragmentation functions for Λ. The calculated fragmentation functions give a good description of all measured observables in Λ production. We predict significant positive longitudinal Λ polarization in inclusive Λ production both in DIS and in proton-proton collisions while models based on SU(3) flavor symmetry predict zero or negative Λ polarization. The effect of Σ and Σ∗ decays is also discussed. Our predictions can be tested at RHIC.