We find a low energy effective action for N = 4 strings manifestly invariant under the full O(6,22,Z) internal duality group. That theory is uniquely specified by its gauge symmetry, which turns out to be an infinite dimensional general Kac-Moody algebra. On any string background the Higgs mechanism leaves only finitely many light fields. The corresponding mass spectrum is studied, and shown to agree with string theory. Orbifold truncations to N = 1, 2 theories are discussed.
ASJC Scopus subject areas
- Nuclear and High Energy Physics