Neutralino relic density with implications for supersymmetry at collider experiments

The relic density of neutralinos produced in the big bang is computed within the framework of the minimal supergravity model. Our calculation is performed at the amplitude level, contains all relevant Feynman diagrams, is fully relativistic, and contains a careful treatment of integration over s-channel annihilation poles. We compare our results with expectations for minimal supergravity at LEP2, the Fermilab Tevatron MI and TeV33 upgrades, the CERN LHC and a next linear collider operating at √(s) = 500 GeV. (orig.)