Classical gauge instantons from open strings

TL;DR

This work establishes a precise open-string framework for gauge theory instantons by analyzing the D3/D(-1) brane system. Mixed disks, with boundary segments on D3 and D(-1) branes, act as sources for the classical instanton fields, and their amplitudes reproduce the BPST instanton profiles in the singular gauge, while the ADHM moduli emerge from the D(-1) sector in the α'→0 limit. The authors derive the full superinstanton solutions by combining unbroken and broken supersymmetries, and they show how to obtain the standard instanton calculus from string amplitudes through a strong-coupling scaling of moduli that yields the ADHM measure. Their framework provides a clean bridge between open-string techniques and field-theory instanton calculations, including how D-instanton induced vertices modify the gauge action. The results offer a practical route to compute nonperturbative effects in N=4 SYM and related theories using string-theoretic tools.

Abstract

We study the D3/D(-1) brane system and show how to compute instanton corrections to correlation functions of gauge theories in four dimensions using open string techniques. In particular we show that the disks with mixed boundary conditions that are typical of the D3/D(-1) system are the sources for the classical instanton solution. This can then be recovered from simple calculations of open string scattering amplitudes in the presence of D-instantons. Exploiting this fact we also relate this stringy description to the standard instanton calculus of field theory.