{\sbb Z}_7 orbifold models in M-theory

Among T7/? orbifold compactifications of M-theory, we examine models containing the particle physics standard model in four-dimensional spacetimes, which appear as fixed subspaces of the 10-dimensional spacetimes at each end of the interval, , spanning the 11th dimension. Using the projection to break the E8 gauge symmetry in each of the four-planes and a limiting relation to the corresponding heterotic string compactifications, we discuss the restrictions on the possible resulting gauge field and matter spectra. In particular, some of the states are non-local: they connect two four-dimensional worlds across the 11th dimension. We illustrate our programmable calculations of the matter field spectrum, including the anomalous U(1) factor which satisfies a universal Green?Schwarz relation, discuss a Dynkin diagram technique to showcase a model with SU(3) ? SU(2) ? U(1)5 gauge symmetry, and discuss generalizations to higher order orbifolds.