GAUGE COUPLING UNIFICATION IN SUPERSTRING DERIVED STANDARD-LIKE MODELS

I discuss gauge coupling unification in a class of superstring standard-like models, which are derived in the free fermionic formulation. Recent calculations indicate that the superstring unification scale is at 0 (10(18) GeV) while the minimal supersymmetric standard model is consistent with LEP data if the unification scale is at 0 (10(16)) GeV. A generic feature of the superstring standard-like models is the appearance of extra color triplets (D, DBAR), and electroweak doublets (l, lBAR), in vector-like representations, beyond the minimal supersymmetric standard model. I show that gauge coupling unification at O(10(18) GeV) in the superstring standard-like models can be consistent with LEP data. I present an explicit standard-like model that can realize superstring gauge coupling unification.