Mass degeneracy of the higgsinos

The search for charginos and neutralinos at LEP2 can become problematic if these particles are almost mass degenerate with the lightest neutralino. Unfortunately this is the case in the region where these particles are higgsino-like. We show that, in this region, radiative corrections to the higgsino mass splittings can be as large as the tree-level values, if the mixing between the two stop states is large. We also show that the degree of degeneracy of the higgsinos substantially increases if a large phase is present in the higgsino mass term μ.