Proposal for non-BPS D-brane action

TL;DR

The paper addresses constructing a non-BPS D-brane action that is both supersymmetric and T-duality covariant, and analyzes how tachyon condensation can realize a BPS D$(p-1)$-brane with κ-symmetry. It proposes a Dirac-Born-Infeld–type action with a tachyon potential $V(T)$, yielding a smooth tachyon kink in the linear regime and reproducing the BPS brane action after condensation, including the WZ coupling. Through comparisons with prior proposals, it argues for a formulation that combines SUSY invariance, T-duality covariance, and sensible kink dynamics, and it discusses how the resulting tensions and charges align with known D-brane data. The work also outlines non-Abelian extensions and links to K-theory, highlighting that further string-theory input is needed to fix the precise form of the non-BPS action.

Abstract

In this short note we would like to propose a form for the action of a non-BPS D-brane, which will be manifestly supersymmetric invariant and T-duality covariant. We also explicitly show that tachyon condensation on the world-volume of this brane leads to the Dirac-Born-Infeld action for BPS D(p-1)-brane.