From the type I string to M-theory: A continuous connection Original Research Article

It is well known that the SO(32) and E8 × E8 heterotic strings can be continuously connected to each other in nine dimensions. Since the strong-coupling duals of these theories are respectively the SO(32) Type I theory and M-theory compactified on a line segment, there should be a corresponding continuous connection between the Type I string and M-theory. In this paper, we give an explicit construction of this dual connecting theory. Our construction also enables us to realize the E8 × E8 × E8 heterotic string as a D-string soliton of the Type I theory. This provides a useful alternative description of the D-brane bound states previously discussed from a Type I′ point of view.