Multibranes boundary states with open string interactions

TL;DR

This paper develops boundary states for multiple parallel branes with open string interactions in bosonic string theory, revealing that open strings inherently encode information about closed strings even at tree level.

Contribution

It introduces a method to derive boundary states for multibrane configurations with arbitrary open string interactions, ensuring vertex commutativity and linking open and closed string sectors.

Findings

Boundary states for multibrane systems are explicitly constructed.

Open string interactions encode closed string information at tree level.

A formalism for computing closed string amplitudes via open string states is provided.

Abstract

We derive boundary states which describe configurations of multiple parallel branes with arbitrary open string states interactions in bosonic string theory. This is obtained by a careful discussion of the factorization of open/closed string states amplitudes taking care of cycles needed by ensuring vertexes commutativity: in particular the discussion reveals that already at the tree level open string knows of the existence of closed string. We also give a formal expression for computing pure closed string amplitudes using the open string formalism.