Supersymmetric World-volume Action for Non-BPS D-branes
Ashoke Sen
TL;DR
The paper develops a supersymmetric world-volume action for non-BPS D-branes in type II theories by identifying it with the supersymmetric DBI term of the κ-symmetric BPS action, with supersymmetry realized nonlinearly on the brane. It shows how to couple this action to background supergravity and explores how extra light fields arising from orientifold/orbifold constructions can be incorporated while preserving symmetry. It also analyzes tachyon condensation, showing that at the tachyon minimum the brane action can vanish and the U(1) gauge field acts as a constraint, leading to the disappearance of charged open-string states. Together, these results provide a coherent framework for the low-energy dynamics of non-BPS D-branes and clarify the fate of gauge fields under tachyon condensation.
Abstract
We construct the world-volume action for non-BPS D-branes in type II string theories. This action is invariant under all the unbroken supersymmetries in the bulk, but these symmetries are realised as spontaneously broken symmetries in the world-volume theory. Coupling of this action to background supergravity fields is straightforward. We also discuss the fate of the U(1) gauge field on the D-brane world-volume after tachyon condensation.