A Two-Instanton Test of the Exact Solution of N=2 Supersymmetric QCD

TL;DR

This paper computes the two-instanton contribution to N=2 supersymmetric QCD's low-energy dynamics using the Atiyah-Drinfeld-Hitchin-Manin solution, confirming Seiberg-Witten predictions for massless and massive cases.

Contribution

It provides a first-principles calculation of the two-instanton effect in N=2 SQCD, validating the Seiberg-Witten exact solution with explicit instanton computations.

Findings

Exact agreement with Seiberg-Witten predictions for all flavors.

Confirmed predictions for massive hypermultiplets.

Validated the two-instanton contribution as the leading non-perturbative effect.

Abstract

The exact solution of N=2 supersymmetric QCD found by Seiberg and Witten includes a prediction for all multi-instanton contributions to the low-energy dynamics. In the case where the matter hypermultiplets are massless, the leading non-perturbative contribution at weak coupling comes from the two-instanton sector. We calculate this contribution from first principles using the exact two-instanton solution of the self-dual Yang-Mills equation found by Atiyah, Drinfeld, Hitchin and Manin. We find exact agreement with the predictions of Seiberg and Witten for all numbers of flavours. We also confirm their predictions for the case of massive hypermultiplets.