Fractional Branes in Non-compact Type IIA Orientifolds

TL;DR

This paper investigates fractional D-branes in a non-compact Type IIA orientifold, revealing stability conditions and proposing a tachyon condensation process leading to stable D-instantons.

Contribution

It provides a detailed analysis of fractional D-branes in a specific orientifold, identifying stability properties and the role of tachyon condensation in their dynamics.

Findings

Fractional D0-branes are unstable due to tachyons.

A stable D-instanton exists with projected-out tachyon.

Whitehead group calculation supports the tachyon condensation hypothesis.

Abstract

We study fractional D-branes in the Type-IIA theory on a non-compact orientifold of the orbifold C^3/Z_3 in the boundary state formalism. We find that the fractional D0-branes of the orbifold theory become unstable due to the presence of a tachyon, while there is a stable D-instanton whose tachyon gets projected out. We propose that the D-instanton is obtained after tachyon condensation. We evidence this by calculating the Whitehead group of the Abelian category of objects corresponding to the boundary states as being isomorphic to Z_2.