Problems for light higgsinos

Abstract

We analyze the possibility that the higgsino mass m h ̃ ⪅ 100 eV as allowed by cosmology. Although permitted at the price of an adjustment of model parameters at the tree-level, such a low value of m h ̃ is technically unnatural since radiative corrections make contributions to m h ̃ of order 100 MeV. If one also postulates thatthe gravitino mass m 3 2 <m h ̃ , so that a light higgsino is unstable and could explain the large ultra-violet background at large redshifts, the scale of supersymmetry breaking must be very low and there would be strong gravitational interactions at energies of order 1 TeV.