SO(10) Yukawa Unification with mu < 0
  We consider the low energy implications including particle spectroscopy of SO(10) inspired t-b-tau Yukawa coupling unification with mu < 0, where mu is the coefficient of the bilinear Higgs mixing term of the minimal supersymmetric standard model (MSSM). We imploy non-universal MSSM gaugino masses induced by SO(10) invariant dimension five operators, such that the total number of fundamental parameters is precisely the same as in Yukawa unified supersymmetric SO(10) models with universal gaugino masses and mu > 0. We find that t-b-tau Yukawa unification with mu < 0 is compatible with the current experimental bounds, including the WMAP bound on neutralino dark matter and the measured value of the muon anomalous magnetic moment. We present a variety of benchmark points which include relatively light squarks (~ TeV) of the first two families and an example in which the bottom and top squarks are lighter than the gluino. This is quite distinct from Yukawa unification with mu > 0 and universal gaugino masses in which the gluino is the lightest colored sparticle and the sqaurks of the first two families have masses in the multi-TeV range. 
Ilia Gogoladze, Qaisar Shafi, Cem Salih Un
hep-ph