D-instanton Effects on a D3-brane

Abstract

It has been proposed by Sen that the D-instanton effects in string theory can be systematically determined through the framework of open-closed string field theory. We apply the latter formalism to analyze the D-instanton corrections to the quantum effective action of a D3-brane in type IIB superstring theory, and determine the leading single and multi-instanton contributions to the $D^4 F^4$ effective coupling which is unprotected by supersymmetry. Notably, while we find that the one-instanton contribution agrees with a conjecture of Green and Gutperle, the multi-instanton contribution disagrees with the conjecture.

Figures (6)

• Figure 1: The worldsheet diagram for the leading D-instanton correction to the amplitude $\mathcal{A}[\mathcal{V}_1,\ldots,\mathcal{V}_n]$ of $n$ 3-3 string modes, with all D(-1) boundaries sharing the same collective coordinates $(x,\theta,\lambda)$.
• Figure 2: Leading D-instanton contribution to the 4-gauge boson amplitude $\mathcal{A}[\mathcal{V}_+,\mathcal{V}_+,\mathcal{V}_-,\mathcal{V}_-]$.
• Figure 3: Contour pull used in equation \ref{['pulleq']}. This relates the deformation of the D-instanton boundary condition to the SUSY transformation of the $\mathcal{V}_\pm$ vertex operator.
• Figure 4: Local coordinate maps $f_a(w_a)$ used to define the 3-vertex $\mathcal{V}_{0,3}$, with $\alpha=2.5$. Each half-circle has the same $|w_a|$, ranging from 0.2 to 1.
• Figure 5: The new coordinates $\hat{z}$ defined on the newly formed disk.