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Vus from hyperon semileptonic decays

Ruben Flores-Mendieta

hep-pharXiv:hep-ph/0410171

Abstract

A model-independent determination of the CKM matrix element Vus from five measured strangeness-changing hyperon semileptonic decays is performed. Flavor SU(3) symmetry breaking effects in the leading vector and axial-vector form factors are analyzed in the framework of the 1/Nc expansion of QCD. A fit to experimental data allows one to extract the value Vus=0.2199 0.0026, which is comparable to the one from Ke3 decays. This reconciliation is achieved through second-order symmetry breaking effects of a few percent in the form factors f1, which increase their magnitudes over their SU(3) predictions.

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