A. Brandhuber et S. Stieberger, SELF-DUAL STRINGS AND STABILITY OF BPS STATES IN N=2 SU(2) GAUGE-THEORIES, Nuclear physics. B, 488(1-2), 1997, pp. 199-222
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 na
turally arises from type-IIB Calabi-Yau compactifications whose three-
branes wrapped around vanishing two-cycles correspond to one-cycles on
this surface.