Supersymmetric grand unification

We construct SU(5) grand unified theories in which the hierarchy problem is solved by supersymmetry broken spontaneously at a very large mass scale. Primordial supersymmetry breaking at the tree level in a gauge singlet O'Raifearteigh sector is fed to gauge non-singlet particles by radiative corrections. Light particle masses are related to the primordial supersymmetry breaking scale by products of chiral and gauge couplings. Squarks and sleptons are naturally heavier than their quark and lepton partners, while gaugions may or may not be heavier than conventional gauge particles. Radiative corrections can relate the scales of SU(5) and supersymmetry breaking and naturally give negative (mass)2 to Higgs fields if the top quark is heavier than O(25) GeV. We work out in some detail the phenomenology of the low-energy effective theory, discussing in particular the masses and couplings of light fermions and Higgs bosons, and mentioning some of their experimental signatures. We also discuss cosmological aspects of our models, emphasizing in particular that finite temperature effects select an intermediate energy SU(3) x SU(2) x U(1) invariant phase. (orig.)