RG FLOW IRREVERSIBILITY, C THEOREM AND TOPOLOGICAL NATURE OF 4-D N=2 SYM

We determine the exact beta function and a RG flow Lyapunov function for N=2 super-Yang-Mills (SYM) theory with the gauge group SU(n). It turns out that the classical discriminants of the Seiberg-Witten curves determine the RG potential. The radial irreversibility of the RG flow in the SU(2) case and the nonperturbative identity relating the u modulus and the superconformal anomaly indicate the existence of a four-dimensional analogue of the c theorem for N=2 SYM theory which we formulate for the full SU(n) theory. Our investigation provides further evidence of the essentially topological nature of the theory.