Creation of Fundamental Strings by Crossing Dirichlet Branes

Abstract

We study the force balance between orthogonally positioned p-brane and $(8\ensuremath{-}p)\ensuremath{-}\mathrm{brane}$. 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 branches. As the p-brane passes through the $(8\ensuremath{-}p)\ensuremath{-}\mathrm{brane}$, 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 ${I}^{\ensuremath{'}}$ theory.