Dark Matter Phenomenology of GUT-less SUSY Breaking

Abstract

We study models in which supersymmetry breaking appears at an intermediate scale, M_in, below the GUT scale. That is, that the soft supersymmetry-breaking parameters of the MSSM are universal at M_in. We demand that the lightest neutralino be the LSP, and that the relic neutralino density not conflict with measurements by WMAP and others, and study the morphology of this constraint as the universality scale is reduced from the GUT scale. At moderate values of M_in, we find that the allowed regions of the (m_1/2,m_0) plane are squeezed by the requirements of electroweak symmetry breaking and that the lightest neutralino be the LSP, whereas the constraint on the relic density is less severe. At very low M_in, the electroweak vacuum conditions become the dominant constraint, and a secondary source of astrophysical cold dark matter would be necessary to explain the measured relic density for nearly all values of the soft SUSY-breaking parameters and tan(beta).