Nonuniversal soft supersymmetry breaking and dark matter

An analysis is given of the effects of nonuniversal soft supersymmetry-breaking masses in the Higgs sector and in the third generation squark sector, and it is shown that they are highly coupled. Nonuniversality effects on dark matter event rates in neutralino-nucleus scattering are analyzed. It is found that the effects are maximal in the range $m_{{\tilde{\chi }}_1}<~65$ GeV where the relic density is governed by the $Z$ and Higgs poles. In this range the minimum event rates can be increased or decreased by factors of $\sim 10$ depending on the sign of nonuniversality. Above this range Landau pole effects arising from the heavy top quark mass tend to suppress the nonuniversality effects. The effect of more precise measurements of cosmological parameters on event rates, which is expected to occur in the next round of COBE-like satellite experiments, is also investigated. Implications for the analysis for dark matter searches are discussed.