Ten-dimensional heterotic string as a soliton

It is shown that the heterotic string emerges as a soliton in the type I superstring theory in ten dimensions. The collective coordinates of the soliton are described by a smooth, chiral worldsheet theory. There are eight bosonic and eight right-moving fermionic zero modes that arise from the partially broken supertranslations. In addition, there are 496 charged bosonic zero modes of the gauge field that describe a left-moving WZNW model on a spin(32)/(Z2) group manifold. Small, stable loops of the solitonic string furnish the massive states required by duality that transform as spinors of spin(32)