N=2 Instanton Calculus In Closed String Background

TL;DR

This paper demonstrates how to derive gauge instanton effects in N=2 super Yang-Mills theory using string scattering amplitudes in a D3/D(-1) brane setup within a Ramond-Ramond background, linking string theory and field theory results.

Contribution

It introduces a method to compute instanton effects in gauge theories via string theory, connecting D-brane systems with gauge instantons and the topological string.

Findings

Computed the gauge theory prepotential using string scattering amplitudes.

Established the equivalence between string-based instanton calculus and topological string results.

Analyzed the interaction of gauge instantons with the graviphoton in a fractional D-brane system.

Abstract

In this contribution we describe how to obtain instanton effects in four dimensional gauge theories by computing string scattering amplitudes in D3/D(-1) brane systems. In particular we study a system of fractional D3/D(-1) branes in a Z_2 orbifold and in a Ramond-Ramond closed string background, and show that it describes the gauge instantons of N=2 super Yang-Mills theory and their interactions with the graviphoton of N=2. Using string theory methods we compute the prepotential of the effective gauge theory exploiting the localization methods of the instanton calculus, showing that this leads to the same information given by the topological string.