%0 Journal Article %T Cold Dark Matter and b --> s gamma in the Horava-Witten Theory %A S. Khalil %A G. Lazarides %A C. Pallis %J Physics %D 2000 %I arXiv %R 10.1016/S0370-2693(01)00366-5 %X The minimal supersymmetric standard model with complete, partial or no Yukawa unification and radiative electroweak breaking with boundary conditions from the Horava-Witten theory is considered. The parameters are restricted by constraining the lightest sparticle relic abundance by cold dark matter considerations and requiring the b-quark mass after supersymmetric corrections and the branching ratio of b --> s gamma to be compatible with data. Complete Yukawa unification can be excluded. Also, t-b Yukawa unification is strongly disfavored since it requires almost degenerate lightest and next-to-lightest sparticle masses. However, the b-tau or no Yukawa unification cases avoid this degeneracy. The latter with mu<0 is the most natural case. The lightest sparticle mass, in this case, can be as low as about 77 GeV. %U http://arxiv.org/abs/hep-ph/0005021v4