Phenomenological study of a minimal superstring standard model

Recently, we demonstrated the existence of heterotic-string solutions in wh ich the observable sector effective field theory just below the string scal e reduces to that of the MSSM, with the standard observable gauge group bei ng just SU(3)(C) x SU(2)(L) x U(1)(Y) and the SU(3)(C) x SU(2)(L) x U(1)(Y) -charged spectrum of the observable sector consisting solely of the MSSM sp ectrum. Associated with this model is a set of distinct Rat directions of v acuum expectation values (VEVs) of non-Abelian singlet fields that all prod uce solely the MSSM spectrum. In this paper, we study the effective superpo tential induced by these choices of flat directions. We investigate whether sufficient degrees of freedom exist in these singlet Rat directions to sat isfy various phenomenological constraints imposed by the observed standard model data, For each hat direction, the effective superpotential is given t o sixth order. The variations in the singlet and hidden sector low energy s pectrums are analyzed. We then determine the mass matrices (to all finite o rders) for the three generations of MSSM quarks and leptons, Possible Higgs mu -terms are investigated. We conclude by considering generalizations of our flat directions involving VEVs of non-Abelian fields. (C) 2001 Elsevier Science B.V. All rights reserved.