Yukawa unification in SO(10)

In simple SO(10) SUSY GUTs the top, bottom and tau Yukawa couplings unify at the GUT scale. A naive renormalization group analysis, neglecting weak scale threshold corrections, leads to moderate agreement with the low energy data. However, it is known that intrinsically large threshold corrections proportional to tanβ~mₜ(MZ)/mb(MZ)~50 can nullify these t, b, {τ} mass predictions. In this paper we turn the argument around. Instead of predicting fermion masses, we use the constraint of Yukawa unification and the observed values Mₜ, mb(mb), M_τ to constrain SUSY parameter space. We find a narrow region survives for μ>0 with μ, M1/2m₁₆, A₀≈-1.9m₁₆ and m₁₆>1200 GeV. Demanding Yukawa unification thus makes definite predictions for Higgs boson and sparticle masses. In particular, we find a light Higgs boson with a mass mₕ⁰=114±5±3 GeV and a light top squark with (m_t₁)MIN~450 GeV and m_t₁m_b₁. In addition, we find a light chargino and a neutralino LSP. It is also significant that in this region of parameter space the SUSY contribution to the muon anomalous magnetic moment a_μSUSY<16×10^-10.