VALUE OF THE KOBAYASHI-MASKAWA-CABIBBO MATRIX ELEMENT-VUS AND FLAVOR-SYMMETRY BREAKING IN HYPERON SEMILEPTONIC DECAYS

We perform a detailed model-independent analysis of the determination of V(us) in the DELTA-S = 1 decays LAMBDA --> pe-nu, SIGMA- --> ne-nu, and XI- --> LAMBDA-e-nu. Values systematically higher than the K(e3) one are obtained. A reconciliation may be only obtained through second-order changes of a few percent in the leading vector form factors f1, provided that these changes always increase their magnitudes over their conserved vector current (CVC) predictions. Using the CVC or the recoil part of recent flavor-symmetry-breaking calculations, the value V(us), = 0.2258 +/- 0.0027 is obtained, which is higher than the K(e3) one by 2.6 standard deviations.