Multi-Instanton Calculus and Equivariant Cohomology
  We present a systematic derivation of multi-instanton amplitudes in terms of ADHM equivariant cohomology. The results rely on a supersymmetric formulation of the localization formula for equivariant forms. We examine the cases of N=4 and N=2 gauge theories with adjoint and fundamental matter. 
Ugo Bruzzo, Francesco Fucito, Jose F. Morales, Alessandro Tanzini