Spin content of Λ in QCD sum rules

Abstract

We calculate the isoscalar axial-vector coupling constants of the Λ hyperon using the method of QCD sum rules. A determination of these coupling constants reveals the individual contributions of the u, d, and the s quarks to the spin content of Λ. Our results for the light-quark contributions are in agreement with those from experiment assuming flavor SU(3). We also find that the flavor-SU(3)-breaking effects are small and the contributions from the u and the d quarks to the Λ polarization are negatively polarized as in the flavor-SU(3) limit.