Predictions of $SU(9)$ orbifold family unification

We study predictions of orbifold family unification models with $SU(9)$ gauge group on a six-dimensional space-time including the orbifold $T^2\mathrm{/}{Z}_2$, and obtain relations among sfermion masses in the supersymmetric extension of models. The models have an excellent feature that just three families of the standard model fermions exist in a pair of Weyl fermions in the $[9,3]$ representation as four-dimensional zero modes, without accompanying any mirror particles.