Supersymmetric dark matter

When combined with the wealth of observational evidence for a nonrelativistic matter density Ω0≳0.3, the big-bang-nucleosynthesis constraint on the baryon density, Ωb≲0.1 indicates the existence of a significant amount of nonbaryonic dark matter. Several lines of reasoning suggest that the dark matter consists of some new, as yet undiscovered, weakly interacting massive particle (WIMP). Of the WIMP candidates that have been considered, perhaps the best-motivated and certainly the most theoretically developed is the neutralino, the lightest supersymmetric particle (LSP) in many supersymmetric theories. There is now a vast experimental effort being mounted to detect these particles in the Galactic halo. Techniques include direct detection in low-background laboratory detectors, indirect detection through observation of energetic neutrinos from annihilation of WIMPs that have accumulated in the Sun and/or the Earth, and observation of anomalous cosmic-ray antiprotons, positrons, and gamma rays.