Closed strings from SO(8) Yang–Mills instantons Original Research Article

When eight-dimensional instantons, satisfying F∧F=±★8(F∧F), shrink to zero size, we find stringy objects in higher order ten-dimensional Yang–Mills (viewed as a low-energy limit of open string theory). The associated F4 action is a combination of two independent parts having a single-trace and a double-trace structure. As a result we get a D-string from the single-trace term and a fundamental string from the double-trace. The latter has (8,0) supersymmetry on the world-sheet and couplings to the background gauge fields of a heterotic string. A correlation between the conformal factor of the instanton and the tachyon field is conjectured.