$Z_3$ orbifold construction of $SU(3{)}^3$ GUT with ${\sin }^2{\theta }_W^0=3/8$

Abstract

It is argued that a phenomenologically viable grand unification model from superstring is $SU(3{)}^3$, the simplest gauge group among the grand unifications of the electroweak hypercharge embedded in semi-simple groups. We construct a realistic 4D $SU(3{)}^3$ model with the GUT scale ${\sin }^2{\theta }_W^0=\frac{3}{8}$ in a $Z_3$ orbifold with Wilson line(s). By two GUT scale vacuum expectation values, we obtain a rank 4 supersymmetric standard model below the GUT scale, and predict three more strange families.

Comments: Latex file of 13 pages