Naturally Light Higgs Doublets in the Supersymmetric Grand Unified   Theories with Dynamical Symmetry Breaking
  We construct a supersymmetric grand unified model in which a dynamical symmetry breaking of SU(5)$_{GUT}$ generates large masses for color-triplet Higgs multiplets while keeping SU(2)$_L$-doublet Higgs multiplets naturally light. The vanishing masses for the Higgs doublets are guaranteed by the Peccei-Quinn symmetry. We also show that the Peccei-Quinn symmetry suppresses the dangerous dimension 5 operators for the nucleon decay. 
T.Yanagida