Higher Derivative Terms in the Effective Action of N=2 SUSY QCD from Instantons

TL;DR

This paper calculates higher derivative corrections in N=2 SUSY QCD using instantons, revealing how singularities in the effective action relate to matter mass values and providing an exact solution for a specific operator.

Contribution

It introduces a method to compute higher derivative terms in the effective action of N=2 SUSY QCD via instanton effects, including an exact solution for a particular operator.

Findings

Higher derivative corrections are computed in various regions of the moduli space.

Singular behavior of a certain operator is linked to charge singularity collisions.

An exact solution for the operator on the Higgs branch is obtained.

Abstract

We consider N=2 SUSY QCD with gauge group SU(2) and N_f flavours of matter with nonzero mass. Using the method of the instanton-induced effective vertex we calculate higher derivative corrections to the Seiberg-Witten result in the momentum expansion of the low energy effective Lagrangian in various regions of the modular space. Then we focus on a certain higher derivative operator on the Higgs branch. We show that the singular behavior of this operator comes from values of mass of matter at which charge singularity on the Coulomb branch collides with the monopole or dyon one. Given the behavior of this operator at weak coupling coming from instantons as well as its behavior near points of colliding singularities we find the exact solution for this operator.