Maximally Supersymmetric String Theories in D<10

Abstract

The existence of maximally supersymmetric solutions to heterotic string theory that are not toroidal compactifications of the ten-dimensional superstring is established. We construct an exact fermionic realization of an N=1 supersymmetric string theory in D=8 with non-simply-laced gauge group Sp(20). Toroidal compactification to six and four dimensions gives maximally extended supersymmetric theories with reduced rank (4,12) and (6,14) respectively.

Comments: LaTex, 10 pages. Additional details of the solutions described here are available on the World-Wide Web at http://www-theory.fnal.gov/superstrings/superstrings.html