Self-dual strings and stability of BPS states in N = 2 SU(2) gauge theories Original Research Article

We show how BPS states of supersymmetric SU(2) Yang-Mills with matter — both massless and massive — are described as self-dual strings on a Riemann surface. This connection enables us to prove the stability and the strong coupling behaviour of these states. The Riemann surface naturally arises from type-IIB Calabi-Yau compactifications whose three-branes wrapped around vanishing two-cycles correspond to one-cycles on this surface.