Ghost D-branes

TL;DR

This paper introduces ghost D-branes as objects canceling ordinary D-branes in superstring theories, explores their gauge symmetries, and generalizes dualities, revealing new brane configurations and string theories with supergroup gauge symmetries.

Contribution

It defines ghost D-branes, analyzes their gauge symmetries, and extends duality frameworks to include ghost branes and supergroup gauge theories in string theory.

Findings

Ghost D-branes cancel effects of ordinary D-branes.

System with D-brane and ghost D-brane at same location is equivalent to vacuum.

New brane configurations and superstring theories with supergroup gauge symmetries are constructed.

Abstract

We define a ghost D-brane in superstring theories as an object that cancels the effects of an ordinary D-brane. The supergroups U(N|M) and OSp(N|M) arise as gauge symmetries in the supersymmetric world-volume theory of D-branes and ghost D-branes. A system with a pair of D-brane and ghost D-brane located at the same location is physically equivalent to the closed string vacuum. When they are separated, the system becomes a new brane configuration. We generalize the type I/heterotic duality by including n ghost D9-branes on the type I side and by considering the heterotic string whose gauge group is OSp(32+2n|2n). Motivated by the type IIB S-duality applied to D9- and ghost D9-branes, we also find type II-like closed superstrings with U(n|n) gauge symmetry.