Dark matter in Susy models

Direct detection experiments for neutralino dark matter in the Milky Way are examined within the framework of SUGRA models with R-parity invariance and grand unification at the GUT scale, M _G. Models of this type apply to a large number of phenomena, and all existing bounds on the SUSY parameter space due to current experimental constraints are included. For models with universal soft breaking at M _G (mSUGRA), the Higgs mass and b → sγ constraints imply that the gaugino mass, m _1/2, obeys m _1/2>300–400 GeV, putting most of the parameter space in the coannihilation domain, where there is a relatively narrow band in the m ₀-m _1/2 plane. For μ>0, we find that the neutralino-proton cross section is ?10^?10 pb for m _1/2<1 TeV, making almost all of this parameter space accessible to future planned detectors. For μ<0, however, there will be large regions of parameter space with cross sections <10^?12 pb and, hence, unaccessible experimentally. If, however, the muon magnetic moment anomaly is confirmed, then μ>0 and m _1/2?800 GeV. Models with nonuniversal soft breaking in the third generation and Higgs sector can allow for new effects arising from additional early Universe annihilation through the Z-channel pole. Here, cross sections that will be accessible in the near future to the next generation of detectors can arise, and can even rise to the large values implied by the DAMA data. Thus, dark matter detectors have the possibility of studying the post-GUT physics that control the patterns of soft breaking.