Abstract :
We consider compactifications of the matrix model of M-theory on S1/Z2 × Td for d > 0, and interpret them as orbifolds of the supersymmetric U(N) Yang-Mills theory on R × Td+1. The orbifold group acts both on the gauge group and on the Td+1, reduces the gauge group to O(N) over 1 + 1-dimensional fixed-point submanifolds, and breaks half of the supersymmetry. We clarify some puzzling aspects of the gauge anomaly cancellation in the presence of spacetime Wilson lines; in general, the Yang-Mills theory requires certain Chern-Simons couplings to supergravity background fields. We discuss the possibility that D8-branes are present as certain matrix configurations in the yang-Mills theory, and the fundamental fermions emerge as zero-modes. Finally, we point out that the correspondence between matrix theory and string theory suggests the existence of a multitude of non-trivial RG fixed points and dualities in orbifold Yang-Mills theories with eight supercharges in various dimensions.
