Evidence for mass dependent effects in the spin structure of baryons

We analyze the axial-vector form factors of the nucleon hyperon system in a model with mass dependent quark spin polarizations. This mass dependence is deduced from an earlier analysis\cite{jlhs,jlhs2} of magnetic moment data, and implies that the spin contributions from the quarks to a baryon decrease with the mass of the baryon. When applied to the axial-vector form factors, these mass dependent spin polarizations bring the various sum-rules from the model in better agreement with experimental data. Our analysis leads to a reduced value for the total spin polarization of the proton.