Fractional branes, confinement, and dynamically generated superpotentials Original Research Article

We examine the effects of instantons in four-dimensional N = 1 supersymmetric gauge theory by including D0-branes in type IIA brane constructions. We examine instanton-generated superpotentials in supersymmetric QCD and find that they are due to a repulsive force between D4-branes bound to D0-branes ending on NS 5-branes. We study situations where instanton effects break supersymmetry such as the Intriligator-Thomas-Izawa-Yangagida model and relate this to a IIA brane construction. We also argue how confinement due to a condensate of fractional instantons manifests itself in super Yang-Mills theory using fractional D0-branes, D4-branes, and NS-strings.