Fundamental strings in Dp-Dq brane systems

TL;DR

This paper analyzes conformal field theory correlation functions involving open strings between different D-branes, deriving differential equations and explicit solutions for boundary twist fields that change boundary conditions.

Contribution

It introduces a Knizhnik-Zamolodchikov-like equation for boundary twist field correlators in D-brane systems and provides explicit integral solutions.

Findings

Derived a differential equation for boundary twist field correlators.

Provided explicit integral formulas for solutions.

Enhanced understanding of open string interactions between D-branes.

Abstract

We study conformal field theory correlation functions relevant for string diagrams with open strings that stretch between several parallel branes of different dimensions. In the framework of conformal field theory, they involve boundary condition changing twist fields which intertwine between Neumann and Dirichlet conditions. A Knizhnik-Zamolodchikov-like differential equation for correlators of such boundary twist fields and ordinary string vertex operators is derived, and explicit integral formulas for its solutions are provided.