Yukawa unification in SO(10) -: art. no. 115004

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 tan betasimilar tom(t)(M-Z)/m(b)(M-Z)similar to50 can nullify these t, b, tau 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 M-t, m(b)(m(b)), M-tau to constrain SUSY parameter space. We find a narrow region survives for mu>0 with mu, M-1/2<<m(16), A(0)approximate to-1.9 m(16) and m(16)>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 m(h)(0)=114+/-5+/-3 GeV and a light top squark with (m(t1))(MIN)similar to450 GeV and m(t1)<m(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(mu)(SUSY)<16x10(-10).