DETERMINATION OF THE KOBAYASHI-MASKAWA-CABIBBO MATRIX ELEMENT V-US UNDER VARIOUS FLAVOR-SYMMETRY-BREAKING MODELS IN HYPERON SEMILEPTONIC DECAYS

We study the success to describe hyperon semileptonic decays of four m odels that incorporate second-order SU(3) symmetry-breaking correction s. The criteria to assess their success is by determining V-us in each of the three relevant hyperon semileptonic decays and comparing the v alues so obtained with one another and also with the one that comes fr om K-l3 decays. A strong dependence on the particular symmetry-breakin g model is observed. Values of V-us which do not agree with the one of K-l3 are generally obtained. However, in the context of chiral pertur bation theory, only the model whose corrections are O(m(s)) and O(m(s) (3/2)) is successful. Using its predictions for the f(1) form factors one can quote a value of V-us from this model, namely, V-us = 0.2176+/ -0.0026, which is in excellent agreement with the K-l3 one.