Light stop decays into Wbχ˜10 near the kinematic threshold

We investigate the decays of the light stop in scenarios with the lightest neutralino χ˜10 being the lightest supersymmetric particle, including flavour-violating (FV) effects. We analyse the region where the three-body decay t˜1→Wbχ˜10 is kinematically allowed and provide a proper description of the transition region between the three-body decay and the four-body decay t˜1→χ˜10bff¯′. The improved treatment has been implemented in the Fortran package SUSY-HIT and is used for the analysis of this region. A scan over the parameter range including all relevant experimental constraints reveals that the FV two-body decay into charm and χ˜10 can be as important as the three-, respectively, four-body decays if not dominant and therefore should be taken into account in order to complete the experimental searches for the light stop.