On the relation between the holomorphic prepotential and the quantum moduli in SUSY gauge theories

We give a simple proof of the relation Λ∂ΛF = i2πb1〈TrΦ2〉, which is valid for N = 2 supersymmetric QCD with massless quarks. We consider SU(Nc) gauge theories as well as SO(Nc) and SP(Nc). An analogous relation which corresponds to massive hypermultiplets is written down. We also discuss the generlizations to N = 1 models in the Coulomb phase.