D-brane Bound States from Charged Macroscopic Strings

TL;DR

This paper constructs new D-brane bound state solutions in string theory by starting from charged macroscopic strings, demonstrating their charge and mass properties, and generalizing to various Dp-brane configurations.

Contribution

It introduces a method to generate D-brane bound states from charged macroscopic string solutions, expanding the known spectrum of bound states in string theory.

Findings

Solutions carry multiple gauge charges and momenta.

Masses and charges satisfy 1/2 BPS bound conditions.

Reductions recover known D-brane bound state solutions.

Abstract

We construct new D-brane bound states using charged macroscopic type IIB string solutions.A generic bound state solution, when dimensionally reduced, carries multiple gauge charges. Starting with D=9 charged macroscopic strings, we obtain solutions in D=10, which are interpreted as carrying (F, D0, D2) charges as well as nonzero momenta. The masses and charges are also explicitly shown to satisfy the non-threshold bound of 1/2 BPS objects. Our solutions reduce to the known D-brane bound state solutions with appropriate restrictions in the parameter space. We further generalize the results to (Dp- D(p+2)) bound state in IIA/B theories, giving an explicit example with p=1.