Closed strings from SO(8) Yang-Mills instantons

When eight-dimensional instantons, satisfying F boolean AND F = +/- (*8) (F boolean AND F), shrink to zero size, we find stringy objects in higher ord er ten-dimensional Yang-Mills (viewed as a low-energy limit of open string theory). The associated F-4 action is a combination of two independent part s 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 doubl e-trace. The latter has (8, 0) supersymmetry on the world-sheet and couplin gs to the background gauge fields of a heterotic string. A correlation betw een the conformal factor of the instanton and the tachyon field is conjectu red. (C) 2001 Elsevier Science B.V. All rights reserved.