Complete one--loop analysis to stop and sbottom decays into $Z$ and $W^{\pm }$ bosons

We study radiative corrections to third generation scalar fermions into gauge bosons $Z$ and $W^{\pm }$. We include both SUSY-QCD, QED and full electroweak corrections. It is found that the electroweak corrections can be of the same order as the SUSY-QCD corrections and interfere destructively in some region of parameter space. The full one loop correction can reach 10% in some SUGRA scenario, while in general MSSM, the one loop correction can reach 20% for large $\tan \beta$ and large trilinear soft breaking terms $A_b$.