F D RATIO IN HYPERON BETA-DECAYS AND THE SPIN DISTRIBUTION IN THE NUCLEON/

It is shown that hyperon beta decay data can be well accommodated with in the framework of Cabibbo's SU(3) symmetric description if one allow s for a small SU(3) symmetry breaking proportional to the mass differe nce between strange and nonstrange quarks. The F/D ratio does not depe nd sensitively on the exact form of the symmetry breaking, and the bes t fits are close to the value previously used in the analysis of deep inelastic scattering of electrons or muons on polarized nucleons. The total quark helicity and strange quark polarization in the nucleon are discussed.