Study of Minimal String Unification in Z8Z_8 Orbifold Models

We study the construction of the minimal supersymmetric standard model from the $Z_8$ orbifold models. We use a target-space duality anomaly cancellation and a unification of gauge couplings as constraints. It is shown that some models obtained through a systematical search realize the unification of SU(3) and SU(2) coupling constants.Comment: 11 pages, KANAZAWA-93-08, LaTeX fil

Minimal String Unification and Constraint on Hidden Sector

We examine whether a minimal string model possessing the same massless spectra as the MSSM can be obtained from $Z_4$, $Z_6$ and $Z_8$ orbifold constructions. Using an anomaly cancellation condition of the target space duality symmetry, we derive allowable values of a level $k_1$ of U(1)$_Y$ for the minimal string model on the orbifolds through computer analyses. We investigate threshold corrections of the gauge coupling constants of SU(3), SU(2) and U(1)$_Y$ and examine consistencies of the model with the LEP experiments. Further we investigate what kinds of hidden sectors are consistent with the minimal string models. Also their gauge coupling constants of the hidden groups are estimated. We discuss Yukawa couplings of the models.Comment: 36 pages, KANAZAWA-94-09, Latex fil