We present detailed calculations of the X̃t̃ 1 coannihilation channels that have the largest impact on the relic ̃X density in the constrained minimal supersymmetric extension of the Standard Model (CMSSM), in which scalar masses m 0 , gaugino masses m 1/2 and the trilinear soft supersymmetry-breaking parameters A 0 are each assumed to be universal at some input grand unification scale. The most important t̃ 1 t̃ 1 * and t̃ 1 t̃ 1 annihilation channels are also calculated, as well as t̃ 1 ̃el coannihilation channels. We illustrate the importance of these new coannihilation calculations when A 0 is relatively large. While they do not increase the range of m 1/2 and hence m χ allowed by cosmology, these coannihilation channels do open up new 'tails' of parameter space extending to larger values of m 0 .
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We thank Toby Falk for many related discussions. The work of K.A.O. and Y.S. was supported in part by DOE grant DE-FG02-94ER-40823.