New Consistent Limits to M-theory and Coupling Constant Quantization

The construction of phenomenologically-viable effective field theories describing M-theory compactified on $S^1/{\bf Z}_2$ is revisited, and new insights into the parameters of the theory are explained. Particularly, the web of constraints which follow from supersymmetry and anomaly cancelation is shown to be more complex than previously understood. One especially interesting result is that, in contradistinction to the current lore on the subject, a consistent classical theory describing the coupling of eleven dimensional supergravity to super Yang-Mills theory constrained to the orbifold fixed points is shown to exist