Creation of Fundamental Strings by Crossing D-branes

TL;DR

The paper investigates force balance between orthogonal D-branes and shows that the attraction balancing repulsion is provided by half a fundamental string, with the connecting string reversing upon brane crossing, i.e. string creation. This creation is derived both from the Chern-Simons structure of D-brane effective actions and from M-theory considerations, and is connected via U-duality to Hanany-Witten-type brane creation of higher-dimensional objects. A chain of dualities maps the process to a 3-brane creation in the Hanany-Witten setup, demonstrating a common origin in M-theory for string/brane creation phenomena. Additionally, the authors analyze heterotic D-particle quantum mechanics in type I', showing the same string-creation effect in a quantum-mechanical framework, thereby unifying the picture across dual descriptions and highlighting the non-perturbative dynamics of brane intersections.

Abstract

We study the force balance between orthogonally positioned $p$-brane and $(8-p)$-brane. The force due to graviton and dilaton exchange is repulsive in this case. We identify the attractive force that balances this repulsion as due to one-half of a fundamental string stretched between the branes. As the $p$-brane passes through the $(8-p)$-brane, the connecting string changes direction, which may be interpreted as creation of one fundamental string. We show this directly from the structure of the Chern-Simons terms in the D-brane effective actions. We also discuss the effect of string creation on the 0-brane quantum mechanics in the type I' theory. The creation of a fundamental string is related by U-duality to the creation of a 3-brane discussed by Hanany and Witten. Both processes have a common origin in M-theory: as two M5-branes with one common direction cross, a M2-brane stretched between them is created.