Heterotic NS5-branes from closed string tachyon condensation

Abstract

We show how to construct the familiar heterotic NS5 brane as a topological soliton in a supercritical version of heterotic string theory. Closed string tachyon condensation removes the extra dimensions, leaving the NS5 in ten dimensions, in a process highly reminiscent of the K-theoretical description of type II D-branes, but linking nontrivial gauge bundles and geometry. This establishes a new kind of equivalence between gravitational and gauge configurations, reminiscent of the gauge/geometry correspondence. We also use the K-theory description to build other heterotic branes as solitons of closed string tachyons. The construction requires a modification of the anomalous Bianchi identity for ${H}_{3}$ in supercritical heterotic string theory. We give various proofs for the existence of this modification.