Classification of Standard Model Particles in $E_6$ Orbifold Grand Unified Theories

Abstract

We classify the standard model fermions, which originate from bulk fields of the $27$ or $\overline{27}$ representation after orbifold breaking, in $E_6$ grand unified theories on 5 or 6-dimensional space-time, under the condition that $q$, $e^c$ and $u^c$ survive as zero modes.

Comments: 24 pages, typos corrected, to appear in IJMPA