Fermionic decays of sfermions: a complete discussion at one-loop order

We present a definition of an on-shell renormalization scheme for thesfermion and chargino-neutralino sector of the Minimal Supersymmetric StandardModel (MSSM). Then, apply this renormalization framework to the interactionbetween charginos/neutralinos and sfermions. A kind of universal corrections isidentified, which allow to define effective chargino/neutralino couplingmatrices. In turn, these interactions generate (universal) non-decoupling termsthat grow as the logarithm of the heavy mass. Therefore the full MSSM spectrummust be taken into account in the computation of radiative corrections toobservables involving these interactions. As an application we analyze the fullone-loop electroweak radiative corrections to the partial decay widths\Gamma(\tilde{f} -> f\neut) and \Gamma(\tilde{f} -> f'\cplus) for all sfermionflavours and generations. These are combined with the QCD corrections tocompute the corrected branching ratios of sfermions. It turns out that theelectroweak corrections can have an important impact on the partial decaywidths, as well as the branching ratios, in wide regions of the parameterspace. The precise value of the corrections is strongly dependent on thecorrelation between the different particle masses.Comment: LaTeX 53 pages, 22 figures, 3 tables. Typos correcte