Gaugino mass nonuniversality and dark matter in supergravity, strings, and D-brane models

The effects of nonuniversality of gaugino masses on dark matter are examined within supersymmetric grand unification, and in string and D-brane models with R parity invariance. In SU(5) unified models nonuniversality in the gaugino sector can be generated via the gauge kinetic energy function which may depend on the 24, 75 and 200 dimensional Higgs representations. We also consider string models which allow for nonuniversality of gaugino masses and D-brane models where nonuniversality arises from embeddings of the standard model gauge group on five-branes and nine-branes. It is found that with gaugino mass nonuniversality the range of the LSP mass can be extended much beyond the range allowed in the universal SUGRA case, up to about 600 GeV even without coannihilation effects in some regions of the parameter space, The effects of coannihilation are not considered and inclusion of these effects may further increase the allowed neutralino mass range. Similarly with the inclusion of gaugino mass nonuniversality, the neutralino-proton (X-p) cross section can increase by as much as a factor of 10 in some regions of the parameter space. An analysis of the uncertainties in the quark density content of the nucleon is given and their effects on the X-p cross section are discussed. The predictions of our analysis including nonuniversality are compared with the current limits from dark matter detectors and implications for future dark matter searches are discussed.