Branes and Electric-Magnetic Duality in Supersymmetric QCD

TL;DR

This paper explores the M theory fivebrane configurations corresponding to N=1 supersymmetric QCD, identifying dual Type IIA limits that represent electric and magnetic descriptions, and extends the analysis to symplectic and orthogonal gauge groups.

Contribution

It demonstrates the smooth interpolation between electric and magnetic configurations in M theory, contrasting with weakly coupled Type IIA string theory approaches.

Findings

Identified effective gauge coupling matching the exact beta function.

Found two distinct Type IIA limits for electric and magnetic SQCD.

Extended analysis to symplectic and orthogonal gauge groups.

Abstract

We study the Type IIA limit of the M theory fivebrane configuration corresponding to N=1 supersymmetric QCD with massless quarks. We identify the effective gauge coupling constant that fits with Novikov-Shifman-Veinshtein-Zakharov exact beta function. We find two different Type IIA limits that correspond to the electric and magnetic descriptions of SQCD, as observed in the massive case by Schmaltz and Sundrum. The analysis is extended to the case of symplectic and orthogonal gauge groups. In any of the cases considered in this paper, the electric and magnetic configurations are smoothly interpolated via $M$ theory. This is in sharp contrast with the proposed derivation of N=1 duality within the weakly coupled Type IIA string theory where a singularity is inevitable unless one turns on a parameter that takes the theory away from an interesting point.