D-Sphalerons and the Topology of String Configuration Space

TL;DR

This paper demonstrates that unstable D-branes act as D-sphalerons, revealing a complex topological structure in the configuration space of Type II string theories with non-trivial homotopy groups.

Contribution

It introduces the concept of D-sphalerons and shows their role in the topology of string configuration space, highlighting a rich homotopy structure.

Findings

Unstable D-branes are identified as D-sphalerons.

Configuration space of Type II string theory has non-trivial homotopy groups.

Homotopy groups are non-zero for all even (or odd) k in Type IIA/IIB.

Abstract

We show that unstable D-branes play the role of ``D-sphalerons'' in string theory. Their existence implies that the configuration space of Type II string theory has a complicated homotopy structure, similar to that of an infinite Grassmannian. In particular, the configuration space of Type IIA (IIB) string theory on $\R^{10}$ has non-trivial homotopy groups $\pi_k$ for all $k$ even (odd).