Taming the supergravity description of non-BPS D-branes: the D/Dbar solution

TL;DR

This paper constructs a supergravity solution for a D-string/anti-D-string pair in an orbifold background, revealing a tensionless probe indicating a potential resolution of singularities via the enhancon mechanism, and contrasting force behaviors with non-BPS descriptions.

Contribution

It provides a supergravity description of non-BPS D-brane bound states and explores their stability and singularity resolution mechanisms.

Findings

Probe becomes tensionless before reaching the singularity.

Enhancon mechanism potentially resolves the repulson-like singularity.

Attractive force observed on the probe contrasts with non-BPS D-brane behavior.

Abstract

We obtain the supergravity solution which describes a bound state of D-string/anti-D-string pairs attached to different fixed planes of an orbifold, in type IIB string theory compactified on T^4/Z_2. For parameters at which the conformal field theory point of view predicts stability, the solution displays a repulson-like singularity. However, we observe that a D-string/anti-D-string pair probe in this background becomes tensionless before reaching the singularity, suggesting a resolution by the enhancon mechanism. Moreover, the force feels by this probe is attractive, in contrast to the repulsive behaviour observed in the non-BPS D-brane description.