Cabibbo theory and hyperon semileptonic decays

A detailed comparison of the Cabibbo theory and hyperon semileptonic decays is performed. Radiative corrections and the $q^2$ dependence of the leading vector and axialvector form factors are considered. Radiative corrections significantly reduce the deviations between theory and experiment and they are the most important out of all the corrections. The overall agreement between theory and experiment is not satisfactory. It is shown that the deviations come mainly from polarization asymmetries in $\Lambda \to \mathrm{pe}\nu$ and ${\Sigma }^{-}\to \mathrm{ne}\nu$; otherwise the agreement with the Cabibbo theory is good. The current situation can be described as a twofold situation. Either the tendency shown by the polarization data is substantially changed or the Cabibbo theory would lose its simplicity.