Stretched strings in tachyon condensation models

TL;DR

This paper models unstable D9 branes in Type IIA string theory, constructing stable D8 brane stacks and analyzing the properties of open string modes stretching between them, consistent with string theory predictions.

Contribution

It introduces a boundary string field theory approach to construct and analyze D8 brane stacks and their open string modes in Type IIA string theory.

Findings

Open string modes are localized between branes.

Masses of modes match string tension predictions.

Mode width is independent of brane separation.

Abstract

In this note, we consider the two derivative truncation of boundary string field theory for unstable D9 branes in Type IIA string theory. We construct multiples of the stable codimension 1 solitons that correspond to stacks of D8 branes. We find the fluctuation modes that correspond to open strings stretching between the branes, and find that their masses are consistent with the string tension. We show that these modes are localized halfway between the branes and that their width is independent of the brane separation.