Monopole supression and baryon production in cosmologies based on Witten's upside down hierarchy model

We demonstrate that the supersymmetric grand unified models proposed by Witten do not lead to an overproduction of superheavy monopoles at the SU(5) phase transition. The causal bound in these theories is consistent with standard cosmology. We discuss baryon production in these theories and argue that in order to produce a sufficient number of baryons, the color triplet Higgs mass must be much lighter than the grand unification scale. This leads to unacceptably large proton decay rates via Weinberg's dimension-5 operator.